What does mildew mean?
Mildew names a fungus or the fungal growth that appears as a soft, powdery, or fuzzy coating on damp vegetation, food, wood, paint, and other organic surfaces. As a noun, it can denote the visible growth itself, an infestation, or the plant disease commonly called powdery or downy mildew. As a verb, mildew describes what happens when something becomes covered with such growth: exposed brickwork can mildew, while poor ventilation may mildew a room. The word is standard in both British and American English and is especially associated with kitchens, bathrooms, cellars, textiles, and neglected buildings, although the organisms also attack crops and ornamental plants. Mildew is related to the wider category called mold in American English and mould in British English, but the term usually points more directly to visible fungal growth or the resulting condition. In everyday use, mildew carries a strongly negative domestic connotation because it suggests dampness, decay, and neglect; in agriculture and horticulture, it is a precise term for important fungal diseases. The word is therefore useful both as a familiar household complaint and as a technical term in plant pathology.
A fungal growth or coating that develops on damp organic material, especially vegetation, food, wood, textiles, or painted surfaces; also an infestation or plant disease caused by mildew fungi.
"A patch of mildew appeared beneath the kitchen window."
The noun is countable when referring to distinct patches, colonies, or infestations and uncountable when referring to fungal growth generally or a disease affecting plants.
To become affected or covered with mildew; to cause something to become covered with mildew.
"The damp corner mildewed within a few weeks."
The verb can be used intransitively for the affected subject or transitively with something as its object.
The plural is used for distinct patches, colonies, infestations, or types of mildew.
"The survey found several mildews spreading across the crop."
Mildew has a mild-sounding name, but a severe case can damage crops, buildings, and the surfaces people live on.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does mildew come from?
The modern word descends from Old English meldew, which was continued in Middle English as meldewe. It is inherited from Proto-Germanic and has close cognates in Dutch meeldauw, German Mehltau, and Swedish möldagg. The exact native development of the compound is uncertain, so its established Germanic history is clearer than any proposed explanation of its individual elements.
Related word forms
How mildew is actually used
Mildew is standard in formal and informal English. As a countable noun, it can refer to individual patches or infestations; as an uncountable noun, it commonly denotes fungal growth generally or a plant disease.
Easily confused with mildew
In American English, mold is the broader category that includes mildew, while mildew usually refers specifically to a visible fungal growth or the infestation it causes; British English normally uses mould for the broader category.