Is there a word for one side in a pair? In a conversation it would the the interlocutor, but I'm looking for a generic term.

  • Example sentence needed in single-word requests. After six years it’s unlikely to be forthcoming, so let’s kill it.
    – David
    Oct 4, 2020 at 19:03
  • 4
    Moiety is that word Oct 5, 2020 at 0:07

10 Answers 10


The English word for "one of a pair" is in fact "pair". You can ask: "Where is the pair to this shoe?" "Pair" has two meanings.

  • But it is not used in isolation for a single member of the set. Dec 20, 2019 at 19:30
  • @EdwinAshworth. Every member of parliament has a "pair" in the opposite party.
    – fdb
    Dec 20, 2019 at 19:49
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    Yes, every MP has a pair. This is not 'in isolation'. I can't pick a random element in a set with two members, take it to show it to a friend, and call it a 'pair'. 'One of a pair', yes. Dec 20, 2019 at 19:55

I'm going with "counterpart", as suggested to me off-site. Thanks for the feedback though!

  • That's great. You should still provide a definition and explain why this word particularly met your need.
    – Kit Z. Fox
    Apr 21, 2014 at 11:47

This is one of those occasions when one realizes the unique abilities of each language. English with most number of words among the world languages, does not have a word for each member of a pair. We, hence, use the word "pair" (as in "where is the other pair?") when we mean a member of the pair. In Persian we do not have this problem as there is a word for members of the dyad. The pair or couple is "Joft" (جفت) and each member of that pair is a "lengeh" (لنگه.) Persian also have a word for a mismatched pair: "lengeh be lengeh!"


  • 1
    Good news and bad news. First the good news. I have found an English term for "one side of a pair." That word is "leg" and it is used in the same sense as the Persian "lengeh" (لنگه) In capital markets usually each trade is logged in a pair, one from the buy and the other from the sell side. You would hear a trader in Wall Street saying "yours didn't match my leg" or "where is the other leg of trade?" Aug 10, 2015 at 1:45
  • The bad news is that this is part of a specialized lingo. But the word is also used in common parlance to refer to the two parts of the itinerary of a trip. What makes this truly exciting is that the words "leg" and "leng" are from the same Indo-European root and they mean exactly the same thing: leng means leg. Aug 10, 2015 at 2:06
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    It is not correct to say that leg refers to one of two parts of a trip. It refers to any one part of a multi-part trip. So your trip could have any number of legs, not just two; to find examples, just search for "this trip has three legs" on google books. As far as the use of leg in capital markets, can you provide some sort of a source? All I found is this and this, both of which sound a bit different from what you are saying. Dec 20, 2019 at 17:11

Until we find a more complicated esoteric word that matches your requirements, try "complement" for a while.

  • Of course something can only be a complement to an aforementioned something else. A boot is not a complement. It's only a complement if you already have the other boot. And then you're still missing a name for that original boot you already have.
    – RegDwigнt
    Apr 19, 2014 at 12:53
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    Are you saying if I order a double vodka then one vodka must be complementary, sounds like a good idea as long as the barmaid doesn't have an account here. :)
    – Frank
    Apr 19, 2014 at 14:34
  • Now I've made a pointless quip I've had a thought. If we agree that one of the pair is the other ones complement then surely the 'aforementioned something else' is also the complement of the other one (the original complement). So in fact any pair is made up of two complements, one half of a pair is a complement, the other half is the other complement.
    – Frank
    Apr 19, 2014 at 14:37

Given that a pair is often referred to by the use of the Greek derived "dyad" you could use "monad" (also derived from the Greek) for a single part of the pair (although monad doesn't specifically describe part of a pair as much as it does a single unit of any kind).




Cugel uses "part" to describe their response, https://english.stackexchange.com/a/164938/227352, so why not just use "part" to describe part of a pair? Everyone knows a pair is only comprised of two objects, so it should be obvious that there could be only two parts.


Odd (Oxford Online Dictionary, def 3): As in the odd glove. Half of a pair.

  • I believe this is the same sense as "odd-man out". This choice is good for many contexts.
    – Kit Z. Fox
    Dec 20, 2019 at 16:45

Partner, as in "howdy partner," based on the latin partitio, "partition"

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    This is wrong. OED: Partner Etymology: Probably an alteration of parcener n. parcener 1. A person who shares, or has a part in, something with another or others; a partner; a sharer, a partaker.)
    – Greybeard
    Oct 17, 2020 at 10:52
  • @Greybeard the Anglo-Norman French parcener, is based on the Latin partitio.
    – gregory
    Oct 17, 2020 at 17:17
  • I see what you mean but, partitio tends to division, whereas parcener goes to mutual interest.
    – Greybeard
    Oct 17, 2020 at 17:28
  • @Greybeard quibbling over the latin's "tendency" to division opposed to its sense of relatedness, I'll refrain from, but wrong I'm not. Besides, the point is that "partner" in English suggests some-one/thing belonging to (or formerly belonging to) a whole: "my partner in life", a "partner in crime", "she's my business partner". As such, it gets pretty close to a word in English "for one side in a pair" which can be used in isolation (see Edwin Ashworth's complaint on the accepted answer). Moreover, "partner" is far more natural than "part" for a pairing, which another answer provided.
    – gregory
    Oct 17, 2020 at 18:28
  • The matter is complicated, though, by the fact that a partnership can have more than two partners.
    – jsw29
    Oct 17, 2020 at 20:52

How about mate, which implies pairing to one other thing, etc, or to a group?

3 : one of a pair: such as

a : either member of a couple and especially a married couple

b : either member of a breeding pair of animals

c : either of two matched objects


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