When should I use "both" and "either"?


Which of the following sentences is correct?

  1. My travel bag has two combination locks, one on either end
  2. My travel bag has two combination locks on either end
  3. My travel bag has two combination locks, one on both ends
  4. My travel bag has two combination locks on both ends


Posted 2014-12-01T10:47:03.230

Reputation: 705

either talks about two and so does 'both'. – Maulik V – 2014-12-01T10:52:40.793

2either talks about "one" and not "two". However, its one out of two. – Rucheer M – 2014-12-01T11:05:56.797

@RuchirM aw..I meant that only! – Maulik V – 2014-12-01T11:46:34.287



This is one of my pet hates…


"…one on each end." or rather, after useful comments,
"...one at each end."

Saves so much confusion.

"two combination locks on either end"
"two combination locks on both ends"

That's 4 locks you have? No, so it can't be those.

one on either end

Colloquial, but OK at a push.

one on both ends

Just clumsy. You can't have 'one on both ends' you need two, unless you can bend the laws of physics.. The one just can't reach to both ends at the same time, it needs its partner at the other end.

Further explanation as to why it ought to be 'each' not 'either' in this scenario

I have a watch chain & one watch. The watch can go on either end of the chain. No confusion, the choice is right there, either end, pick which end you attach it to.

I now have a watch chain & 2 watches. I can attach them to each end. I cannot attach them to either end, because as soon as I've attached the first one, I have no choice then but to attach the other one to the other end. I can no longer attach it to either end.

Also, the football example, of how to really fall over when getting this wrong…
"In football they have two goalkeepers, at either end…"
Sorry, no they don't. The goalkeepers don't get to choose which end they stand at, otherwise they could both choose the same end. They must stand one at each end.

BTW, I realise this is extreme pedantry, & that you could easily get away with most of the alternative suggestions, but I'm just trying to nail this one down logically

gone fishin' again.

Posted 2014-12-01T10:47:03.230

Reputation: 10 773

1is your imperative, Use ____ a personal preference/suggestion or a correction? :-) – Jim Reynolds – 2014-12-01T11:28:29.443

Both ;) It is simply the least confusing way to describe the situation. People fall over this one so frequently - even natives - that you get bizarre constructions like "In football they have two goalkeepers, at either end…" – gone fishin' again. – 2014-12-01T11:31:03.807

More employment in the sports industry. o.o – Jim Reynolds – 2014-12-01T11:36:34.930


There's nothing wrong with "either end"; it's fairly common, even in formal writing (perhaps more so).

– psmears – 2014-12-01T14:06:59.513

@psmears: Those examples describe different situations. For example, a train has a control cab at "either end" to allow it to be controlled by an operator at either end of the train. If operation of the train would require that both cabs be occupied simultaneously, then it would be more appropriate to say "two cabs--one at each end". I've never seen a suitcase which has two combination locks but could be opened in its entirety using only one. If the OP were describing such a suitcase, then "either end" would be appropriate, but I've never seen one. – supercat – 2014-12-01T18:14:58.250

@supercat My problem with 'either' is that I have a watch chain but only one watch. The watch can attach to either end. Leads to confusion when dealing with more than one object, though none with a single object. 'each end' obviates unnecessary explanation when we are discussing using 2 things, one at each end…. & I really don't get your bit about the train, makes no sense to me, nor a single-opening pair of locks. – gone fishin' again. – 2014-12-01T18:20:41.183

@Tetsujin: If I read an elevator described as having doors which open on "either" side, that would suggest that one set of doors opens at some floors, and another set opens at other floors; it would say nothing about whether people who entered via the front would leave via the back nor vice versa. If it were described as having doors that open on "both" sides, that would imply to me that there were some floors where both sets of doors could open simultaneously. If it were described as "each" side, that would imply that everyone who enters via one door would leave via the other. – supercat – 2014-12-01T18:45:27.303

@Tetsujin: To offer an example familiar to even more people, if a room with doors marked "A" and "B" is described as having light switches near "either" door, that would generally suggest that the room has some lights which may be turned on and off by the switch near door "A", and that those same lights may also be turned on and off by the switch near door "B". By contrast, saying it has light switches near "each" door would suggest that door "A" has switches that control some lights, and door "B" has some switches that control some (probably different) lights. – supercat – 2014-12-01T18:54:13.153

@Tetsujin: I guess the question to ask when picking "each" or "either" is whether a person using the apparatus in typical fashion would have to use "each" part, or could use "either" one and ignore the other. – supercat – 2014-12-01T18:59:49.860

@supercat: It might be nice if that were true, but it's not... look through all the examples and you'll see there are plenty where "either end" is clearly used to mean "both ends" (and the sentence would make no sense with an alternative reading). In some situations "either" can imply a sense of "one or the other", but in others it is simply a synonym for "both". Unfortunately this is a situation where usage overrules logic... – psmears – 2014-12-01T20:05:52.450

@psmears: Consider example A46. I would read that as indicating that both ends of the room had screens that showed all the results, such that someone wanting to see all the results [the normal way the screens would be used] could look at screens at either end. If the sentence had used "both", I would take that as indicating that every result was shown on a screen somewhere, but not necessarily indicating that each individual result was shown at both ends. – supercat – 2014-12-01T20:20:22.617

@supercat: You are at liberty to interpret it that way. I think that, often as not, you will be reading into it a meaning that the original writer never intended. For instance "The busiest routes are carved up by bilateral deals between the national airlines at either end." (ABJ): the bilateral deals must be between airlines at both ends - or they wouldn't be bilateral! "So, it's essentially a straight wire with workstations at intervals along its length, and terminators at either end." (CTX): it definitely means "both ends" as such a network will not function with either terminator missing. – psmears – 2014-12-01T20:54:12.417

@psmears: Your last example brings up a point I'd neglected to mention--using a countable but uncounted plural noun with "either" often implies "one at each", but that's different from "one at either"; that does not imply that "either" and "each" are interchangeable, however, since such a plural with "each" would imply that there could be multiple things at each end. As you note, saying "one terminator at each end" would be different from saying "one terminator at either end". – supercat – 2014-12-01T21:13:47.453

@supercat: Wait, what? "One terminator at either end" would definitely signify "one terminator at each end" in this context - compare "A hard little matching satin bolster tucked in at either end" (GUK), or "[There was a rug], with a pattern of stripes and a fringe at either end" (GW2), or many other examples :). I know it feels like there ought to be a rule, but the evidence shows it's just not followed in practice... – psmears – 2014-12-01T21:49:32.950

Let us continue this discussion in chat.

– supercat – 2014-12-01T21:58:15.937

Tetjusin, we are not discussing physics here; we are discussing English grammar. Here, like the question of "why learn English", I would request you to refer to any dictionary, especially The Free Dictionary, for the meanings of "both" and "either". I am sure you Will be convinced. – Khan – 2014-12-06T09:34:00.380

I really can't be bothered with the pointless bickering. If you think I'm wrong, downvote me. – gone fishin' again. – 2014-12-06T10:50:05.783


Numbers 1 and 3 are OK.

At may be preferred by some to designate the location (end). On tends to suggest a surface.

Either has more than one meaning, including:

2 each of two The offices on either side were empty. There's a door at either end of the corridor.

Both also has more than one meaning:

1 ... ‘the two’ or ‘the one as well as the other’

Published examples:

Dual-swivel hose fittings. Most we tested have one at both ends of the hose to help prevent kinks.

Date 2007 (Mar) Publication information Vol. 72, Iss. 3; pg. 40, 3 pgs Title WET/DRY VACS: For big jobs, it's in the bag Source Consumer Reports

(speech) Ms-CUTCHER: We both saw him straddling the body basically, a foot on both sides of Trayvon's body and his hands pressed on his back.

Date 2012 (120325) Title Latest on the shooting of Trayvon Martin Source NBC_Dateline

So what does that all mean? Advocates on both sides of the case took Kennedy's statements as a signal that he and the court will rule in their favor.

Date 2012 (120328) Publication information A-SECTION; Pg. A01 Title Watchers on both sides play guessing game Author David A. Fahrenthold;N.C. Aizenman Source Washington Post

Jim Reynolds

Posted 2014-12-01T10:47:03.230

Reputation: 9 616

+1 for 'at' - that hadn't really bothered me so I didn't correct it, but I do prefer it. – gone fishin' again. – 2014-12-01T11:41:23.663

I don't much like #1 (it should be *each*, not *either*). But my -1 is for saying #3 is "standard" - I find that one completely unacceptable. – FumbleFingers Reinstate Monica – 2014-12-01T13:54:34.577

@FumbleFingers Are you contesting a fact or expressing a personal dissatisfaction with the way people use this language? I'm not sure why you emphasize standard. If it's not clear, I mean that the texts violate no widely accepted rules of grammar propounded by recognized authorities. I've expanded my answer to try to show how the uses so conform, though I'd be happy to see a contradictory fact. It wouldn't surprise me. – Jim Reynolds – 2014-12-01T15:05:01.467

I guess we're working to different definitions of "standard". Google Books claims 378 instances of one on both ends, wherein I can see straight away many are "accidental collocations" anyway. Compare that to 490,000 instances of one on each end. To me, that's a preference of well over 1000:1 in favour of the standard version, regardless of any explicitly-formulated grammatical principles.

– FumbleFingers Reinstate Monica – 2014-12-01T15:19:21.530

Ok. But we need to distinguish common from correct, no? Though I may have run ahead of myself uncarefully. I think [one/singular noun] on both ends/sides/plural noun] might reasonably be deemed incorrect, at least by some "experts/authorities". Maybe I'll try to dig around some more myself. – Jim Reynolds – 2014-12-01T15:52:23.647

Amended answer. – Jim Reynolds – 2014-12-01T16:52:37.957

1+1. As to *"one on either end"*, that seems to be standard usage, w.r.t. MWCDEU "either" entry which has the example: "The two men walked one on either side of the cart --James Stephens The Crock of Gold, 1912". – F.E. – 2014-12-01T17:48:10.333

As to *"one on both ends"*, that sounds okay to me. Consider: "There was a guard at all the entrances into the building" and "There was a guard at both entrances into the building". -- And so, the previous version of your answer-post was probably okay, but your current version is suspect (imo) unless you're willing to now also include some vetted grammatical sources that cast doubt on the acceptability of "one on both ends". :) . . . Actually, there's "Put one on both ends", and there's no question about its acceptability. I think you should do a rollback to the previous version. – F.E. – 2014-12-01T18:01:13.153

@F.E.: The terms "either" and "each" have somewhat different meanings. If a device has controls on "either" end, that would suggest that the controls may be used interchangeably; saying it has controls on "each" end would suggest that they cannot. On the kinds of locking cases I've seen, after someone uses the controls at one end to dial in the combination, the user would then have to use the controls at the other end to finish unlocking the case. I would describe such cases by saying either that they have locks at both ends, or that they have two locks--one at each end. – supercat – 2014-12-01T18:26:37.750

1@F.E. supercat: I have revised the answer again. I think it is simplified as is, and more could be said. But I don't think the sentences 1 and 3 can fairly be proclaimed incorrect. Careful writers and speakers may want to avoid such expressions as a house on both sides of the hill as ambiguous, and maybe a guard at both entrances for the same reason, but always avoiding such seems more a matter of taste than avoiding grammatical error. – Jim Reynolds – 2014-12-01T18:40:42.373

I disagree, supercat. Either has more than one meaning, one of which is each. No matter the system mechanics, I think that normally both locks on a case with two locks need to be unlocked to complete an opening. The kind of difference you describe does not require a change in language in order to state that there are two locks, one on each side / one on both sides. – Jim Reynolds – 2014-12-01T18:46:26.213

@JimReynolds: The term "each" would be a perfect fit if the locks behave as distinct non-interchangeable entities. The term "either" is longer, and the use of a longer term in cases where a shorter term would suffice tends to suggest [but does not positively imply] that the shorter term was unsuitable. If I read a case described as having an electronic-lock keypad at either end, I would guess, in the absence of further information, that both keypads would most likely operate the same primary "mechanism". For a case with mechanical locks, I'd likely expect discrete mechs since I've never... – supercat – 2014-12-01T20:09:11.313

...seen a case with interconnected mechanical lock controls. On the other hand, I have seen doors which could be locked and unlocked from either side, as well as doors which can be locked from "both" sides [and--if locked from a particular side--must be unlocked from that same side before it can be opened]. – supercat – 2014-12-01T20:13:40.130

@supercat - the locks are separate entities. Your confusion of the entire issue is just… ermm… confusing. most of your examples - locks from either or both sides of a door etc., don't clarify, they merely obfuscate. We have a case. It has 2 locks. You need to unlock both to open the case. The locks are located ...wait for it... at each end of the case. they are not at either end, they are at a specific end each. they don't move about, they are fixed. There are locks at both ends, but each lock is at a specific end. – gone fishin' again. – 2014-12-01T21:21:58.727

@Tetsujin: If the locks are independent, and it is expected that both will be operated in normal use (as is typical), I would generally favor using "...a lock at each end"; saying "locks at either end" might be reasonable if securing the case only required the use of one lock (on many cases, if one lock is secured but the other is not, the unsecured end may be easily pulled open far enough to tamper with the contents; the whole purpose of having two locks--one at each end--is to prevent that). – supercat – 2014-12-01T21:50:47.450


"Either" is a determiner; it means "each of two". "Both" is also a determiner; it also means the one and the other or each of two.

1- My travel bag has two combination locks, one at either end. The sentence sounds natural and grammatically correct. There are two locks together. We can rephrase this sentence as "My travel bag has a combination lock at either end". It also means a total number of two locks.

2- "My travel bag has two combination locks at either end". It's not correct if you mean two locks altogether. This sentence indicates a total of four locks.

3- "My travel bag has two combination locks, one at both ends" (each of two sides). This sentence is also grammatically correct; it means a total number of two locks.

4- "My travel bag has two combination locks at both ends". It's not correct as it means that there are four locks; two at one end and two at the other end.

I think if we use either or both in a right way, it makes no difference.



Posted 2014-12-01T10:47:03.230

Reputation: 26 261

Could the number 3 be rephrased as follows: "My travel bag has a combination lock at both ends" ? – Robbo – 2014-12-01T19:01:10.923

A good, clear answer. +1 – Jim Reynolds – 2014-12-01T19:06:20.540

1@Robbo I say yes, it could be so rephrased. Some will say that each end is better, but that's a matter of opinion and does not render both ends incorrect. – Jim Reynolds – 2014-12-01T19:11:06.760

1To my ear, the construct "a widget at either end" implies an expectation that someone needing a widget could arbitrarily select an end, use the widget there, and ignore the other. If the case is unlocked it might be possible to secure it using the lock at "either" end, but if one did so it would (for typical cases and locks) only be possible to open it using the lock on the particular end that was used previously. To my ear, "ether end" would generally suggest that one could secure the case with the lock at either end, and still be able to open it with either end. – supercat – 2014-12-01T20:03:40.367

I would appreciate if the person who has downvted enlighten me in light of the explanation of both and either in the dictionaries, esp. The Free Dictionary. – Khan – 2014-12-03T11:32:13.253