So the plural form of this is 'львы́'? Wikipedia does not indicate that this is irregular. Are there other nouns that follow this pattern, or some sort of rule to help me remember this?

  • 1
    I don't know any rule for this, probably one should memorize the declension for each word, but other examples of this pattern are numerous: сон — сны, ров — рвы, рот — рты, etc.
    – d.k
    May 19, 2017 at 17:53
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    Actually, if you are talking about the Bulgarian currency and not the animal, then the plural will still be "левы". I doubt that there is a fixed rule. May 19, 2017 at 18:31
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    there's no need to stress the vowel - since it's a single-syllable word.
    – shabunc
    May 19, 2017 at 21:14

1 Answer 1


It's not irregular. The mobile vowel is a typical phenomenon for [almost] any masculine singular, non-loan word consisting of two syllables, starting with a singular consonant and taking -и/-ы (and not / ) as a plural marker. The syllable structure is either CVC(ь), CVCVC(ь) or, as some user had put it above, CVCъ (historically).

The one-syllable words are tricky about mobile vowels to predict, but for most polysyllabic words of these types with -ок, -ень or -ец you can be 99% sure that they have a mobile vowel within.

That is, the following forms are rather 'usual' than 'exceptional'.

отец => отцы

ловец => ловцы

малец => мальцы

палец => пальцы

лоб => лбы

лёд => льды

огонь => огни

камень => камни

песок => пески

лоток => лотки

каток => катки

носок => носки

кусок => куски

селезень => селезни

слизень => слизни

The 'regular' forms are in fact more exceptional, cf:

пирог => пироги

порог => пороги

олень => олени

пароль => пароли

пол => полы

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    First time I see such vowels called "mobile". Such "disappearing" vowels are normally called "fleeting vowels". Google this and you'll find a lot of information on the topic. May 19, 2017 at 20:11
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    Or google "беглые гласные" in Russian.
    – V.V.
    May 20, 2017 at 3:42
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    They are named e.i.t.h.e.r. 'fleeting vowels' o.r. 'mobile vowels'. I guess they could be named 'dropped vowels', 'shifting vowels', 'ghost vowels' or otherwise as well.
    – Manjusri
    May 20, 2017 at 9:34
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    Well... actually there is an irregularity about "лев". Its nominative would be expected to be "лёв". There are only about three or four words where the stressed fleeting vowel is not o (orthographically о or ё) - лев, хребет, один and maybe I forgot one.
    – Viridianus
    Feb 6, 2018 at 9:15

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