Entry 1 sense Webster, 1913 Fiorin · Fi·o·rin · IPA /ˈfɪəɹɪn/ 01 n. A species of creeping bent grass (Agrostis alba); -- called also fiorin grass. 1. A species of creeping bent grass (Agrostis alba); -- called also fiorin grass.(Bot.) Also: fiorin grass