Floruit (or fl.) (sometimes italicized to show it is Latin) refers to a period during which a person, school, movement or even species was active or flourishing. It is the 3rd person, singular, perfect tense form of the Latin verb florere 'to flourish' It is widely used in genealogy and to a lesser extent history when the birth or death dates are unknown. Italic can refer to: Italic languages Italic scripts Italic means Of or from Italy; the usage is most commonly restricted to talking about the people and languages of what is now Italy from the historic period before the Roman Empire. ... Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ... Genealogy is the study and tracing of family pedigrees. ...

For example we might have several wills attested by John Jones in 1204, 1207 and 1229, and a record of his marriage in 1197, we would write "John Jones (fl. 1197-1229)".