-ment

To form an adverb in French, follow these steps based on the adjective's ending:

• Standard Rule: Take the feminine singular form of the adjective and add -ment.
  Example: heureuse (happy) → heureusement (happily). Adjectives ending in -ique (like tragique or public/publique) simply follow this standard rule (tragiquement, publiquement).
• Vowel Ending: If the masculine singular adjective already ends in a vowel (such as -i, -u, or -é, but not a silent -e), add -ment directly to the masculine form.
  Example: vrai (true) → vraiment (truly); poli (polite) → poliment (politely); aisé (easy) → aisément (easily).
  Note: Adjectives with irregular feminine forms (like nouveau, fou, mou) use their feminine base (nouvellement, follement, mollement). Also, 'gai' becomes 'gaiement' (or 'gaîment' / 'gaiment'). Some adjectives ending in -u add a circumflex (assidu → assidûment, cru → crûment), though the 1990 spelling reform makes this optional (assidument, crument). An exception is 'impuni', which becomes 'impunément'.
• -ant / -ent Ending: Adjectives ending in -ant replace that ending with -amment, and those ending in -ent replace it with -emment. Both are pronounced the same (the 'e' in -emment sounds like an 'a').
  Example: courant (fluent/common) → couramment (fluently/commonly); prudent (prudent) → prudemment (prudently).
  Note: Common exceptions are lent (lentement) and présent (présentement).
• Accent Changes: For some adjectives, the silent -e at the end of the feminine form changes to an -é- for phonetic reasons.
  Example: précise → précisément (precisely); profonde → profondément (profoundly); énorme → énormément (enormously).

While this is the most common way to form adverbs, some very common ones like bien, mal, and vite do not follow this pattern. Other common irregular forms include gentiment (from gentil, dropping the 'l') and brièvement (from bref). Finally, be careful with invariable adjectives used as adverbs (e.g., parler fort, coûter cher, travailler dur). These do not take a -ment ending! Also, keep in mind that many of the most common adverbs of quantity and frequency (like beaucoup, peu, trop, assez, souvent) are not derived from adjectives at all. Unlike in English, French adverbs generally go after the conjugated verb (e.g., Il court rapidement), not before it.