Why is the plural version of deer identical to the singular version?

If mouse became mice, then why did the singular deer not change to something else in the plural?

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    Many words are, and that is the joy of, and what is infuriating about English. You may be glad to hear however of something I discovered only today, when we were at an animal park with our grandchildren. That is that the word 'mongoose' has two possible plurals, 'mongeese, and mongooses'. And I am a native speaker of English of almost seventy years. So I hope that illustrates that there is no quick way with these things. It takes a lifetime.
    – WS2
    Aug 3, 2014 at 17:48
  • ya thats right it take long time.but right now for me its really important to know all about it.
    – khyati
    Aug 3, 2014 at 17:57
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    Aug 3, 2014 at 18:19
  • Related (possible dupe): Why is “shrimp” the plural of “shrimp” Aug 3, 2014 at 20:16
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    @BlessedGeek this is a good question for experts, linguists and etymologists, as stated by the site. This type of request cannot be answered and explained by the vast majority of native speakers. Compared to the related question "Why is shrimp the plural of shrimp? this question has a more authoritative and complete answer. StoneyB's post lacks (if any observation were to be levelled) back up source(s) and references.
    – Mari-Lou A
    Aug 4, 2014 at 6:04

2 Answers 2


It's a matter of historical origin and subsequent development.

In the oldest recorded English deer belonged to the neuter declension, which did not have a distinct plural ending in the nominative and accusative cases. (It is believed that this declension did have plurals in Proto-Germanic, but they disappeared before English or any immediate ancestor was written down.) At that time there was no ambiguity, since the determiners accompanying these nouns did change in the plural.

Later, when the Old English endings were mostly lost, the majority of these neuter nouns acquired 'regular' plural endings in -n, eventually superseded by endings in -s: wīf, for instance, became wives in the plural. A few, however did not, and deer is one of these.

It is often remarked that all these nouns with invariant plurals denote animals, deer, sheep, fish, swine, which are either herded or hunted; and it has been suggested that both the 'mass noun' sense with herd animals and the custom of referring to all hunted animals in the singular (we hunt bear, lion, and elephant as well as deer) helped inhibit plural regularization.

ADDED: See the second edition (1954) of Jespersen, A Modern English Grammar on Historical Principles, Part II SYNTAX (First Volume), Ch.III The Unchanged Plural (pp. 49–69), especially 3.1–3.2 and 3.71.

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    +1 deers is still noted in OED as an occasional plural the most recent (in the 2nd Ed.) dated at 1817.
    – Frank
    Aug 3, 2014 at 19:52
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    does deers have the same meaning as fishes, e.g. multiple different species of deer?
    – KutuluMike
    Aug 3, 2014 at 23:46
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    @MichaelEdenfield: (1) To my mind, yes: Deers can be used to mean kinds of deer (members of the deer family). I would have no hesitation in saying "Alces alces and Cervus canadensis are deers." (2) I'm no authority.
    – Drew
    Aug 4, 2014 at 2:22
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    Is French influence the reason why plural in -s superseded plurals in -n? Aug 4, 2014 at 8:31
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    @StoneyB but what about 'sleeping with the fishes'? It's clearly the fishes and not the fish ;) Apr 24, 2015 at 14:06

A good answer of StoneyB. I can only add that the lack of distinction between plural and singular forms of some old nouns (which logically must have this distinction) exists in many languages and can be traced back to the ancient state of the language, where the same word was used to describe both the class of elements and one particular element. For example, such a peculiarity still can be found in Korean or Chinese - you usually don't bother about plural ending, unless you want to emphasize the plurality.

  • Just what is the plural ending for Chinese? There isn't any as far as I am aware of except for people.
    – user21820
    Apr 24, 2015 at 6:15
  • @user21820 Oh, you are quite right, I put it in rather an awkward way about Chinese. Whilst Koreans can stress plurality by a lot of special means (the simplest one is just adding plural ending ~tŭl), the Chinese can do that only by using context words - three deer, a few deer, a lot of deer.
    – K. Karavaj
    May 10, 2015 at 11:49
  • Yup. Or for some single words, doubling is allowed, like 人人 or 星星 or 天天日日.
    – user21820
    May 10, 2015 at 12:29

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