Pierre is not simply more intelligent than the other kids in his class, he is the most intelligent in the school (le plus intelligent de l’école). To express that someone (or thing) is the one out of so many, the superlative always includes the definite article the. In French you have to choose between le, la, or les, depending on the gender and number of the noun described.
The superlative of superiority uses le/la/les plus (the most), and the superlative of inferiority uses le/la/les moins (the least).
How to express French superlatives in two ways
Because French articles and adjectives show the gender and number of the noun they accompany, for each superlative in English like the most intelligent, French has four: one for masculine singular (MS) and one for plural (MP), and one for feminine singular (FS) and one for the plural (FP). Be sure to match the definite article and the adjective to the subject you’re describing.
For example, here are the four posssible forms of the superlative adjective intelligent in French:
MS: le plus intelligent
FS: la plus intelligente
MP: les plus intelligents
FP: les plus intelligentes
You can express the superlative in two ways:
Use le/la plus or le/la moins + singular adjective in matching gender. For example: la plus gentille (the kindest).
In plural, use les plus/les moins + plural adjective in matching gender. For example: les moins grands (the least tall).
Use this formula after c’est (he is/she is/it is/this is), as in C’est la plus gentille (She’s the kindest).
Add a noun with a matching definite article in front of the superlative, like this: le/la/les + noun + le/la/les plus or le/la/les moins + adjective in matching gender and number.
For example: le garçon le moins intelligent (the least intelligent boy), la fille la plus intelligente (the most intelligent girl), les chiens les plus fidèles (the most faithful dogs).
Use this formula in the same context as the shorter version, or at the beginning or end of a complete sentence.
At the beginning: La femme la plus bavarde est assise derrière moi. (The most chatty woman is sitting behind me.)
At the end: Ils ont adopté les chiens les plus fidèles. (They adopted the most faithful dogs.)
Put some special French adjectives in their place
In French, most adjectives go after the noun they describe. For example: une voiture rouge (a red car). It’s the opposite in English! However, some adjectives don’t like to follow. For instance beau (beautiful), jeune (young), grand (tall), petit (short), bon (good), and a few more precede the noun they describe, like this: une belle rose (a beautiful rose).
To make a superlative with such adjectives, French has two options:
Place the preceding adjective before the noun, following the rule of placement of such adjectives. (This option is the shortest.)
Place the preceding adjective after the noun, like a regular adjective. (This option is longer.)
To form the shorter (and more common) superlative, follow these steps:
Change the article to a definite one (if it isn’t already), but leave the adjective before the noun.
For example, une jolie fille (a pretty girl) becomes la jolie fille.
Add plus before the adjective.
Like this: la plus jolie fille. Easy, right?
To form the longer superlative, follow these steps:
Change the article to a definite one (if it isn’t already) and change the word order so that the adjective follows the noun.
For example, une jolie fille (a pretty girl) changes to la fille jolie.
Insert le plus, la plus, or les plus before the adjective, making sure to match the number and the gender of the noun.
For example, you have la plus jolie, make sure both definite articles are the same, like this: la fille la plus jolie (the prettiest girl). Both articles must match the noun in gender and number.
Here are some more examples of the two versions of preceding adjectives in a superlative. Note how English has only one way of expressing the same thing:
la plus petite souris/la souris la plus petite (the smallest mouse)
les meilleures tartes/les tartes les meilleures (the best pies)
You have two placement options only with adjectives that typically come before the nouns they describe. For adjectives that normally follow nouns, there’s only one place for the adjective in a superlative.
Add a category with a superlative
A superlative featuring an adjective can also express the category where that one perfect pearl comes from. In English, you can say the smartest in the class; or the prettiest in the world. To add categories in French, the superlative is followed by de (of) and the name of the category with the definite article like de la classe (in the class).
When de is followed by the definite article le, it changes to du. When it is followed by les, it changes to des.
Here are examples of the superlative with its origin expressed:
le plus intelligent de la classe (the smartest in the class)
la plus belle fille du monde (the most beautiful girl in the world)
le plus mignon des animaux (the cutest of animals)
les meilleurs jours de l’année (the best days of the year)