préviennent

Préviennent is the third-person plural present indicative form of the French verb prévenir. It corresponds to the English “they warn” or “they prevent,” depending on the context. The same spelling also appears in the present subjunctive (qu’ils préviennent), where mood is determined by the clause it appears in.

Prévenir is a transitive verb with two main senses. In the sense of warning, informing about a danger or informing someone in advance, it is used with an indirect object: prévenir quelqu’un de quelque chose. Example: Ils préviennent les habitants d’un danger. In the sense of preventing or forestalling, it can take a direct object: Cette mesure peut prévenir les accidents.

Etymology traces prévenir to Latin praevenire, from prae- “before” and venire “to come,” passing into Old French as prévenir. The sense broadened from foreseeing to taking action to avert negative outcomes.

Grammatical note: préviennent is the standard form for ils/elles in the present tense. The form is identical in the present indicative and the present subjunctive (in clauses introduced by que), with distinction implied by context. Préviennent can be used with various complements to express warning, informing, or preventative action.