Hypanthium \Hy*pan"thi*um\, n.; pl. L. {Hypanthia}, E. {Hypanthiums}. [NL., fr. Gr. "ypo beneath + 'a`nqos flower.] (Bot.) A fruit consisting in large part of a receptacle, enlarged below the calyx, as in the {Calycanthus}, the rose hip, and the pear.