French adverbs

Adverbs in French, like in English, are used to modify adjectives, other adverbs, and verbs or clauses. They do not display any inflection; that is, their form does not change to reflect their precise role, nor any characteristics of what they modify.

Formation

In French, as in English, most adverbs are derived from adjectives. In most cases, this is done by adding the suffix -ment to the adjective's feminine singular form. For example, the feminine singular form of lent is lente, so the corresponding adverb is lentement ; similarly, heureux → heureusement.
As in English, however, the adjective stem is sometimes modified to accommodate the suffix:

If the adjective ends in an i, then -ment is added to the masculine singular form, rather than to the feminine singular form:
* vrai → vraiment
* poli → poliment
If the adjective ends in -ant or -ent, then the -nt is stripped and -mment is added:
* constant → constamment
* récent → récemment
Some adjectives make other changes:
* précis → précisément
* gentil → gentiment

Some adverbs are derived from adjectives in completely irregular fashions,
not even using the suffix -ment:

bon → bien
mauvais → mal
meilleur → mieux
traditionally, pire → pis or more commonly, pire → pire

And, as in English, many common adverbs are not derived from adjectives at all:

ainsi
vite

Placement

The placement of French adverbs is almost the same as the placement of English adverbs.
An adverb that modifies an adjective or adverb comes before that adjective or adverb:complètement vrai pas possible trop bien cuit
An adverb that modifies an infinitive generally comes after the infinitive:

marcher lentement

But negative adverbs, such as pas, plus, and jamais, come before the infinitive:

ne pas marcher

An adverb that modifies a main verb or clause comes either after the verb, or before the clause:Lentement il commença à marcher or Il commença lentement à marcher
Note that, unlike in English, this is true even of negative adverbs:Jamais je n'ai fait cela or Je n'ai jamais fait cela