The rule forbidding hiatus in French verse which has been followed in all literary poetry since Malherbe's day may be thus formulated:—

A word ending in a vowel other than an e muet cannot be followed within the same line by a word beginning with a vowel or h muette.

Where a word ends in an e muet and the following word begins with a vowel or an h muette, the e muet is elided and the hiatus thus avoided.

For the purposes of this rule the t of et is supposed not to exist.

Oui is sometimes treated as though it began with a consonant.

Hiatus is allowed before or after a few interjections; also in certain set expressions such as peu à peu, cà et là, and the like.