any of various diseases of plants that affect mainly the leaves and are caused by parasitic fungi
See also powdery mildewany fungus causing this kind of disease - another name for
mould 2
to affect or become affected with mildew
WordReference Random House Learner's Dictionary of American English © 2026
mil•dew /ˈmɪlˌdu, -ˌdyu/USA pronunciation
n. [uncountable]
v.
WordReference Random House Unabridged Dictionary of American English © 2026- Plant Diseasesa cottony coating on plants, fabrics, etc., caused by fungi:mildew on the pages of the old diary.
v.
- to (cause to) become affected with mildew: [no object]The book had mildewed over the years.[~ + object]The book had been mildewed by moisture.
mil•dew
(mil′do̅o̅′, -dyo̅o̅′),USA pronunciation n.
v.t., v.i.
mil′dew′y, adj.
- Plant Diseasesa disease of plants, characterized by a cottony, usually whitish coating on the surface of affected parts, caused by any of various fungi.
- Fungiany of these fungi. Cf. downy mildew, powdery mildew.
- any of similar coatings or discolorations, caused by fungi, as that which appears on fabrics, paper, leather, etc., when exposed to moisture.
v.t., v.i.
- to affect or become affected with mildew.
- bef. 1000; Middle English: honeydew, mildew; Old English mildēaw, equivalent. to mil- honey (cognate with Gothic milith, akin to Latin mel, Greek méli) + dēaw dew
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