mildew

1 of 2

noun

mil·​dew ˈmil-ˌdü 

-ˌdyü

1

a

: a superficial usually whitish growth produced especially on organic matter or living plants by fungi (as of the families Erysiphaceae and Peronosporaceae)

b

: a fungus producing mildew

2

: a discoloration caused by fungi

mildewy

ˈmil-ˌdü-ē 

-ˌdyü-

adjective

mildew

2 of 2

verb

mildewed; mildewing; mildews

transitive verb

: to affect with or as if with mildew

intransitive verb

: to become affected with mildew

Examples of mildew in a Sentence

Noun

The basement's damp walls were covered with mildew.

Recent Examples on the Web

Noun

Body soil, soap scum, mineral deposits, and mildew are common culprits in a dirty shower. — Mary Marlowe Leverette, The Spruce, 28 June 2026

During the hot rainy season some varieties are more susceptible to fungal leaf spots and mildew. — Tom MacCubbin, The Orlando Sentinel, 27 June 2026

Verb

Of course, that is a gift that expires, one that quickly mildews into a curse. — Richard Lawson, vanityfair.com, 9 Oct. 2017

On a recent day, the inside walls of the home were mildewed and the clothes still in the closet were showing spots. — Mimi Whitefield, miamiherald, 5 Oct. 2017

Word History

Etymology

Noun

Middle English, from Old English meledēaw honeydew; akin to Old High German militou honeydew

First Known Use

Noun

14th century, in the meaning defined at sense 1a

Verb

1552, in the meaning defined at transitive sense

Phrases Containing mildew

• downy mildew
• powdery mildew

Rhymes for mildew

• accrue
• ado
• ainu
• aircrew
• airscrew
• anew
• askew
• baboo
• babu
• bamboo
• beaucoup
• bijou

Kids Definition

mildew

1 of 2 noun

mil·​dew ˈmil-ˌd(y)ü 

: a usually whitish growth produced on decaying material or living plants by fungi

also : a fungus producing mildew

mildewy

-ˌd(y)ü-ē 

adjective

mildew

2 of 2 verb

: to affect with or become affected with mildew

Medical Definition

mildew

noun

mil·​dew ˈmil-ˌd(y)ü 

1

: a superficial usually whitish growth produced especially on organic matter or living plants by fungi (as of the families Erysiphaceae and Peronosporaceae)

2

: a fungus producing mildew