Mold \Mold\, Mould \Mould\, n. [From the p. p. of OE. moulen to become moldy, to rot, prob. fr. Icel. mygla to grow musty, mugga mugginess; cf. Sw. m["o]gla to grow moldy. See {Muggy}, and cf. {Moldy}.] (Bot.) A growth of minute fungi of various kinds, esp. those of the great groups {Hyphomycetes}, and {Physomycetes}, forming on damp or decaying organic matter. [1913 Webster] Note: The common blue mold of cheese, the brick-red cheese mold, and the scarlet or orange strata which grow on tubers or roots stored up for use, when commencing to decay, are familiar examples. --M. J. Berkley. [1913 Webster]