dry rotTranslate dry rot | into German | into Italian | into Spanish Definition of dry rot noun 1 [mass noun] fungal timber decay occurring in poorly ventilated conditions in buildings, resulting in cracking and powdering of the wood. 2 (also dry rot fungus) the fungus that causes dry rot decay. Serpula lacrymans, family Corticiaceae, class Hymenomycetes dry rot in other Oxford dictionaries Definition of dry rot in the US English dictionary