Floruit (often abbreviated fl. or flor. and sometimes italicized to show it is Latin) refers to a period of time during which a person, school, movement or even species was active or flourishing. It is the third person, singular, perfect tense form of the Latin verb florere — 'to flourish'. It is widely used in genealogy, and to a lesser extent historical writing, when the birth or death dates are unknown.

A general chronological measurement for a generation, usually thirty years. See lifespan, "reasonable-age concept."