Entry 1 sense Webster, 1913 Hare's-ear /(hârz"ēr`)/ · Hare's·-ear · IPA 01 n. An umbelliferous plant (Bupleurum rotundifolium); -- so named from the shape of its leaves. 1. An umbelliferous plant (Bupleurum rotundifolium); -- so named from the shape of its leaves.(Bot.)