mildew

nouns

the process of becoming mildewed
mildew, mold, mould
a fungus that produces a superficial (usually white) growth on organic matter
mildew
is a type of (narrower)
an organism of the kingdom Fungi lacking chlorophyll and feeding on organic matter; ranging from unicellular or multicellular organisms to spore-bearing syncytia
fungus

verbs

become moldy; spoil due to humidity
"The furniture molded in the old house"
mildew, mold