Lesson: Forming Plurals of French Words Ending in -OU: Rules and Exceptions


Welcome to today’s lesson where we’ll explore how to form the plurals of French words ending in -ou. While the general rule is straightforward, involving simply adding an ‘s’ to the singular form, there are some notable exceptions that you’ll need to remember.

General Rule

For the majority of words ending in -ou, the plural is formed by simply adding an ‘s’ at the end.


  • un clou (a nail) → des clous (nails)
  • un trou (a hole) → des trous (holes)
  • un cou (a neck) → des cous (necks)
  • un fou (a madman) → des fous (madmen)
  • un caribou (a caribou) → des caribous (caribous)
  • un chouchou (a favorite) → des chouchous (favorites)
  • un écrou (a nut, as in nuts and bolts) → des écrous (nuts)
  • un gourou (a guru) → des gourous (gurus)
  • un kangourou (a kangaroo) → des kangourous (kangaroos)
  • un voyou (a thug) → des voyous (thugs)

⚠️ Exceptions

There are seven words that end with ‘ou’ in the singular form but take an ‘x’ instead of an ‘s’ to form their plurals. These words are:

  • bijou (a jewel)
  • caillou (a pebble)
  • chou (a cabbage or term of endearment)
  • genou (a knee)
  • hibou (an owl)
  • joujou (a toy)
  • pou (a louse)

The plural forms of these exceptions are as follows:

  • un bijou → des bijoux (jewels)
  • un caillou → des cailloux (pebbles)
  • un chou → des choux (cabbages or terms of endearment)
  • un genou → des genoux (knees)
  • un hibou → des hiboux (owls)
  • un joujou → des joujoux (toys)
  • un pou → des poux (lice)

Note: The majority of words ending in -ou follow the general rule and adopt an ‘s’ in the plural. Only the seven words listed above form their plural with an ‘x’.

Practice Exercise
Convert the following singular words into their correct plural forms:

This lesson will help you understand and apply the rules for forming plurals in French for words ending in -ou, enhancing your grammatical accuracy when writing and speaking.

Keywords : French plurals -OU, Plural forms in French, French grammar plurals, -OU ending words in French, French plural exceptions