Plural in compound nouns

1. As a rule in compounds it is the second component that takes the plural form:

housewives, tooth-brushes, boy-scouts, maid-servants.

2. Compounds in -ful have the plural ending at the end of the word:

handfuls, spoonfuls, mouthfuls, (though spoonsful and mouthsful are also possible).

3. Compounds in which the first component is man or woman have plurals in both first and last components:

men-servants, women-doctors, gentlemen-farmers.

4. Compounds ending in -man change it into -men in spelling. In pronunciation, however, there is no difference between the singular and plural forms, both having [ǝ]:

policeman [ǝn] - policemen [ǝn].

Such nouns as German, Roman, Norman are not compounds, and therefore they have regular plurals:

Germans, Romans, Normans.

5. In compounds originating from a prepositional noun phrase where the preposition is a linking element only the first noun takes the plural form:

editors-in-chief, mothers-in-law, commanders-in-chief, coats-of-mail, men-of-war (военные корабли).

6. In compounds with a conjunction as a linking element the plural is taken by the second noun:

gin-and-tonics.

7. In compound nouns formed by a noun plus a preposition,or anadverb, or an adjective only the first element takes the plural:

passers-by, lookers-on, courts-martial, attorneys-general.

8. When the compound is a substantivized phrase which doesnot contain a noun, the last element takes the plural ending –s:

forget-me-nots, breakdowns, stand-bys, grown-ups, close-ups,

pick-ups (случайные знакомства),

drop-outs (дезертиры),

go-betweens (посредники).

Invariable nouns

Invariable nouns cannot change their number, some of them are always singular in meaning (linguistics, news), some denote plurality (cattle, police).