Compound nouns:

Plural Forms of Compound Nouns:

  • Generally, the plurals of compounds are formed by pluralizing the main element of the compound: fathers-in-law.
  • Some compounds have two plural forms. Here are two additional examples (the first form is preferred): courts-martial, court-martials.
  • When a hyphenated compound does not contain a noun, the final element can be pluralized: know-it-alls.


brother-in-law                        brothers-in-law
man-of-war                           men-of-war
step-daughter                       step-daughters
step-mother                          step-mothers
passer-by                             passers-by
sergeant major                      sergeants major
assistant headmaster            assistant headmasters
passer-by                             passers-by   

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