several words, probably unrelated, including: 1. "pendant point of cloth on a garment," late 14c., of uncertain origin; 2. "thin rain, drizzle, wet fog," Scottish, late 17c., from a Scandinavian source such as Old Norse dögg, plural daggir "dew," from Proto-Germanic *daowo- (source of Old English deaw; see dew); 3. "kind of heavy pistol," 1560s, of uncertain origin; 4. "clot of dirty wool about the rear end of a sheep," 1731; 5. "tough but amusing person," Australian and New Zealand slang, 1916.

popular name of a woodland bramble or its fruit, which is black with a bluish dewy bloom, 1570s, from dew + berry. a name variously applied in England and North America.

also dew-drop, c. 1200, deawes drope, "a drop of dew;" see dew + drop (n.). Compare German Thautropfen, Danish dugdraabe.

1620s, "the falling of the dew," from dew + fall (n.); hence "early evening," the time when the dew begins to fall.

"thermometer temperature when dew begins to be deposited," hence "that temperature of air at which the moisture present in it just saturates it," 1833; see dew + point (n.).

Old English deawig "of or pertaining to dew; moist with or as with dew;" see dew + -y (2).

also honey-dew, 1570s, "sticky sweet substance found in small drops on trees and plants," from honey (n.) + dew (n.); Similar formation in Dutch honigdaauw, German Honigthau. honeydew melon first recorded 1916, a cross between cantaloupe and a South African melon.

"minute parasitic fungus that appears on plants or decaying organic matter," mid-14c., a transferred sense of a word that meant originally "nectar, honeydew" (the sugar-rich sticky stuff secreted by aphids feeding on plant sap); this is from mid-13c. as mildeu, from Old English meledeaw, from a Proto-Germanic compound of *melith "honey" (from PIE root *melit- "honey") + *dawwaz "dew" (see dew). Similar formation in Old Saxon milidou, Dutch meeldauw, Old High German miltou, German Meltau "mildew." The first element in many continental Germanic languages has been assimilated to forms of meal (n.2) "ground grain."

As a kind of morbid fungus or blight, it presumably is so called from its being sticky and growing on plants. As a verb, "to taint with mildew," from 1550s. Related: Mildewed; mildewy.