Sclerotium \Scle*ro"ti*um\, n.; pl. {Sclerotia}. [NL., fr. Gr. sklhro`s hard.] 1. (Bot.) A hardened body formed by certain fungi, as by the {Claviceps purpurea}, which produces ergot. [1913 Webster] 2. (Zool.) The mature or resting stage of a plasmodium. [1913 Webster]