How to form French adjectives (masculine, feminine, plural forms etc)

In French, the form of an adjective potentially depends on the noun it corresponds with. The form of the adjective, or at least its spelling, usually changes depending on the gender (whether the noun is masculine or feminine) and on the number (whether it is singular or plural).

As far as spelling is concerned, the most general rules are as follows:

add -e to the masculine form to get the feminine form (if it doesn't already end in -e);
add -s to the singular form to get the plural form (if it doesn't already end in -s).

Masculine or feminine?

If you're wondering why the word for book is masculine, or the word for car is feminine, the answer is basically that it "just is". If you look a word up in the French dictionary, it will tell you whether that word is masculine or feminine. And a vocab book will often put le or la before a word to indicate masculine or feminine. In some cases, there are patterns (so actually, all words ending in -ure tend to be feminine). See the section on le or la in French for more information.

These two rules combine, so that a feminine plural adjective ends in -es (imagine adding an -e and then adding an -s).

The "basic" form of an adjective— e.g. the one that you'll find listed in a dictionary— is generally the masculine singular form. The other forms are then made by applying rules to this basic form.¹

On the next page, you'll be able to practice French adjectives that use the above rules. First, let's look at some complete examples.

Example with the adjective vert

The adjective meaning green is vert. Here is how this adjective looks, given the four possible combinations of masculine/feminine and singular/plural. For now, we take it for granted that this adjective follows the noun in French, but the position of adjectives is a topic we'll need to come back to later.

Number	Gender
Number	Masculine	Feminine
Singular	No extra ending un livre vert a green book	Add -e une voiture verte a green car
Plural	Add -s des livres verts (some) green books	Add -es des voitures vertes (some) green cars

Note also in these examples that we had to pick the correct form of the article:

un to mean "a" before a masculine noun (words that refer to a male person, or which usually have le before them in a vocab book);
une to mean "a" before a feminine noun (words that refer to a female person, or which usually have la before them in a vocab book);
des to mean "some"— and note that this word can't be left out in French, as it can sometimes in English.

Example with adjectives already ending in an -e or -s

Now, we'll look at examples of adjectives where one or other of the above rules doesn't need to be applied. Remember that the overall pattern is still the same: a feminine adjective needs to end in -e and a plural adjective needs to end in -s, and a feminine plural adjective in -es. But:

If the form we're about to add an ending to already has that ending, then we don't add it again.

Example with the adjective français

So firstly, here is an example with the adjective français, meaning French, where the basic masculine form ends in an -s. Because the masculine form already ends in -s, no new -s is added in the masculine plural form. Note that one is still added in the feminine plural because, once the feminine -e ending is added, the word no longer ends in -s:

Number	Gender
Number	Masculine	Feminine
Singular	No extra ending un garçon français a French boy	Add -e une fille française a green car
Plural	No extra ending, because the adjective already ends in -s des garçons français (some) French boys	Add -es des filles françaises (some) French girls

Example with the adjective rouge

The French adjective rouge, meaning red, ends in an -e. This means that in the feminine, we won't add another -e. But in the plural, we will still add an -s. So this gives the following forms:

Number	Gender
Number	Masculine	Feminine
Singular	No extra ending un livre rouge a red book	No extra ending: adjective already ends in -e une voiture rouge a red car
Plural	Add -s des livres rouges (some) red books	Adjective already ends in -e, so just add -s des voitures rouges (some) red cars

Exercise

It's worth taking a moment now to read through the above and make sure you've understood it. On the next page, you'll be able to practise what you're learnt with the first French adjective exercise.

Further rules/irregularities

If you'd rather not do the exercises just now, then you may want to go on and have a look at a special case of adjectives ending in -n which double the -n in the feminine.

You may also want to look in more depth at how to form the plural in French: there are a few cases where the simple rule of adding -s is actually not enough.

1. In principle, we could see things the other way round (e.g. with the rule listed here, we could list the feminine form as the "basic" form and then say "remove the -e to get the masculine form"). But there are one or two reasons for treating the masculine form as the "base" form. Firstly, a practical one: practically all dictionaries and vocabulary books treat the masculine as the base form. And from a theoretical point of view, the masculine form is in some sense the "basic" or "unmarked" form, since it's the one that speakers fall back on when there's no obvious reason to pick either masculine or feminine— for example, when referring to a mixture of masculine and feminine nouns, when referring to "no noun in particular" (c'est grand, not ~~c'est grande~~) or when using an adjective as an abstract noun (l'important, not ~~l'importante~~ = the important thing).

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