In French, nouns have two genders (masculine and feminine) attached to them and knowing them is important to better understand and use the language as it affects a lot of it.
The rules of plural nouns
In general when nouns become plural, an –s is added to the end of words.
Ex. la porte → les portes (the doors)
Singular nouns that end with –s –x and –z do not change when they become plural.
Ex. le prix → les prix (the prices)
Singular nouns that end with –eau –eu and –au become plural by adding –x at the end.
Ex. le cheveu → les cheveux (the hair)
However, there are common exceptions which include bleu (blue) and pneu (tire) where an –s is added on instead.
Singular nouns that end with –al become plural by changing into –aux.
Ex. l’animal → les animaux (the animals)
However, there are common exceptions which include festival (festival) and carnaval (carnival) where an –s is added on instead.
Singular nouns that end with –ail become plural by adding on an –s
Ex. Le detail → Les détails (the details)
However, there are common exceptions which include travail (work) which change into –aux.
Singular nouns that end with –ou become plural by adding –s
Ex. Le sou → Les sous (The pennies (not to be confused with the preposition sous))
However, there are common exceptions which include bijou (jewelry), chou (cabbage), genou (knee) and hibou (owl) where an –x is added on instead.
No rule plural nouns
It is possible that some nouns don’t follow the rules mentioned earlier and have unique spellings of their own where the learner has to remember them by heart.