mid-13c., mildeu "honeydew, nectar," from Old English meledeaw "honeydew" (sticky stuff exuded by aphids), from Proto-Germanic compound of *melith "honey" (see Melissa) + *dawwaz "dew" (see dew). Cf. Old Saxon milidou, Dutch meeldauw, German Meltau "mildew."
First element in many cases assimilated to forms of meal (n.2) "ground grain." As a kind of fungus it is first recorded mid-14c., so called from its being sticky and originally growing in plants. As a verb from 1550s. Related: Mildewed.
Any of various fungi or oomycete organisms that form a white or grayish coating on surfaces, such as plant leaves, cloth, or leather, especially under damp, warm conditions. Powdery mildews are important plant diseases usually caused by ascomycete fungi, while downy mildews, including a serious disease of grapevines, are caused by oomycetes.
(the rendering of a Hebrew word meaning "to be yellow," yellowness), the result of cutting east winds blighting and thus rendering the grain unproductive (Deut. 28:22; 1 Kings 8:37; 2 Chr. 6:28).