floruit UK /ˈflɔːɹʊɪt/US /ˈflɔɹ(j)uɪt/noun 1verb 1forms 1 noun1 •The time period during which a person, group, culture, etc. is at its peak. verb1 •Lived, flourished; used in biographies to indicate a time period during which a person is known to have been alive or known to have been notably active, when dates of birth and/or death are not known.Marius Mercator must have shared the vigour of Alcimus, for he floruit in 218 according to Mr. Miller , while he at any rate existed in 418. — 1895 formsfloruits