The Collaborative International Dictionary of English v.0.48:
Hazelnut \Ha"zel*nut`\ (h[=a]"z'l*n[u^]t`), n. [AS. h[ae]selhnutu.] The nut of the hazel. --Shak. [1913 Webster]WordNet (r) 3.0 (2006):
hazelnut n 1: any of several shrubs or small trees of the genus Corylus bearing edible nuts enclosed in a leafy husk [syn: hazelnut, hazel, hazelnut tree] 2: nut of any of several trees of the genus Corylus [syn: hazelnut, filbert, cobnut, cob]