The reason for this special adjective form is to avoid hiatus (the pause between a word that ends in a vowel sound and another that begins with a vowel sound). The French language likes words that flow one into the next, so when an adjective that ends in a vowel sound would otherwise be followed by a word that begins with a vowel sound, French uses a special form of the adjective to avoid the undesirable hiatus. These special forms end in consonants so that an enchaînement is created between the two words, and the fluidity of the language is maintained.
There are nine French adjectives in three categories which have one of these special pre-vowel forms.
The following descriptive adjectives have a special form that is used only in front of a masculine noun that begins with a vowel or mute H.
- beau > bel
un beau garçon > un bel homme
fou > fol
un fou rire > un fol espoir
mou > mol
un mou refus > un mol abandon
nouveau > nouvel
un nouveau livre > un nouvel article
vieux > vieil
un vieux bâtiment > un vieil immeuble
When the demonstrative adjective is used with a masculine noun that begins with a vowel or mute H, it changes from ce to cet:
- ce garçon > cet homme
When a singular possessive adjective is used with a feminine noun that begins with a vowel or mute H, it changes from the feminine form (ma, ta, sa) to the masculine form (mon, ton, son):
- ma mère > mon amie
ta femme > ton amante
sa profession > son éducation
The special adjective forms are used only when followed immediately by a word that begins with a vowel or mute H. If a word which begins with a consonant is placed between the changeable adjective and the noun, the special form is not used.
- cet homme vs ce grand homme
- mon amie vs ma meilleure amie