Demonstrative adjectives are used to designate a specific noun in context. They always accompany a noun and present it as identifiable by the context, by sight, by what has just been said, or by what is being pointed to. In this book, this street, these children, the adjective does not describe the noun as a qualifying adjective would: it shows it. Without it, the noun remains more general. With it, we know which object, which person or which idea is being targeted. Their functioning is based on the same logic as other determinants studied in Adjectifs and also prepares the use of the Demonstrative Pronouns.

The demonstrative adjectives have four base forms. Ce is used with a masculine singular noun: ce garçon. Cet is used with a masculine singular noun that begins with a vowel or a mute h: cet ami, cet hôpital. Cette is used with a feminine singular noun: cette table. Ces is used with a plural noun, masculine or feminine: ces chats, ces maisons. The form depends only on the noun it accompanies. To correctly form these adjectives, one must know the rules of Formation de l'Adjectif.

The demonstrative adjective agrees in gender and number with the noun. It does not express masculine or feminine by itself: it takes them from the noun. A masculine singular noun takes ce or cet, a feminine singular noun takes cette, a plural noun takes ces. The function of the noun in the sentence does not change the form. In je vois ce chien, ce chien is the subject or the object depending on the structure, but the adjective remains the same because it depends only on chien. This agreement relationship follows the general logic explained in Accord de l'adjectif.

Before a masculine singular noun, the choice between ce and cet depends on the initial sound of the noun. We write ce before a consonant: ce train, ce manteau. We write cet before a vowel and before a mute h: cet avion, cet homme. We keep cette before a feminine singular noun, whatever the initial sound: cette amie, cette école. With the aspirated h, we write ce: ce héros, ce haricot. The letter h prevents liaison like a consonant. The position of the adjective remains in front of the noun, in accordance with the Position de l'adjectif.

You can add -ci or -là after the noun to specify distance or to distinguish two elements. -ci marks proximity, -là marks distance or the second element of an opposition: ce livre-ci, ce livre-là, cette femme-ci, ces chaussures-là. In conversation, -là can also be used to emphasize a person or thing already identified: ce type-là, cette idée-là. When both forms appear together, -ci often indicates the closer one and -là the farther one: ce sac-ci et ce sac-là. The demonstrative then keeps its role of precise designation.

The demonstrative adjectives appear when the noun can be identified without further explanation. They are used for an object that you are showing, for a person already mentioned, for an idea already known in the context, or for something present in the situation. Ferme cette porte works because the door is visible or identifiable. J’ai aimé ce film works because the film is known to the interlocutors. Cette remarque est juste designates a precise idea in the discourse. They also help to refer back to an element in a comparison or a description after having clearly stated it: Cette ville est ancienne. Ces rues sont étroites.

It is necessary to distinguish the demonstrative adjective from the demonstrative pronoun ce. As an adjective, ce always accompanies a noun: ce livre, ce moment. As a pronoun, ce replaces a noun or an entire idea: Ce est impossible is not correct, but C’est impossible is, because ce forms a fixed construction with être. In ce qui compte, ce does not accompany a noun; it introduces a repeated idea. The demonstrative adjective behaves like the other determinants studied in Adjectifs qualificatifs, whereas the demonstrative pronoun belongs to the system of Pronoms démonstratifs.