Old English wifel "small beetle," from Proto-Germanic *webilaz (source also of Old Saxon wibil, Old High German wibil, German Wiebel "beetle, chafer," Old Norse tordyfill "dung beetle"), cognate with Lithuanian vabalas "beetle," from PIE root *(h)uebh- "to weave," also "to move quickly" (see weave (v.)). The sense gradually narrowed by 15c. to a particular kind of beetle that, in larval or adult stages, bores into plants, often destroying them.
1510s, "benevolent goblin supposed to haunt old farmhouses in Scotland," diminutive of brown "a wee brown man" (see brown (adj.)).
The brownie was believed to be very useful to the family, particularly if treated well by them, and to the servants, for whom while they slept he was wont to do many pieces of drudgery. In appearance the brownie was said to be meager, shaggy, and wild. [Century Dictionary]
As "small square of rich chocolate cake," often with nuts, 1897. As a brand-name of a type of inexpensive camera, 1900. The name for the junior branch of the Girl Guides or Girl Scouts is by 1916, in reference to their uniform color. Brownie point "notional credit for an achievement; favour in the eyes of another, esp. gained by sycophantic or servile behaviour" [OED] is by 1959, sometimes associated with Brownie in the Scouting sense but is perhaps rather from brown-nose.
type of cereal plant, Middle English ote, from Old English ate (plural atan) "grain of the oat plant, wild oats," a word of uncertain origin, possibly from Old Norse eitill "nodule," denoting a single grain, itself of unknown origin. The English word has cognates in Frisian and some Dutch dialects. Famously defined by Johnson as, "A grain, which in England is generally given to horses, but in Scotland supports the people." Related: Oats.
The usual Germanic name is derived from Proto-Germanic *khabran (source also of Old Norse hafri, Dutch haver, source of haversack). Figurative wild oats "youthful excesses" (the notion is "crop that one will regret sowing") is attested by 1560s, in reference to the folly of sowing these instead of good grain. Hence, feel (one's) oats "be lively," 1831, originally American English.
That wilfull and vnruly age, which lacketh rypenes and discretion, and (as wee saye) hath not sowed all theyr wyeld Oates. [Thomas Newton, "Lemnie's Touchstone of complexions," 1576]
Fred: I still want to sow some wild oats!
Lamont: At your age, you don't have no wild oats, you got shredded wheat.
["Sanford and Son"]
1560s, a general term of endearment (also puggy), perhaps related to or a variant of puck (n.2); one of the earliest senses of pug is "sprite, imp" (1610s). The sense of "miniature dog" is from 1749 (pug-dog); that of "monkey" is from 1660s, perhaps on the notion of having a pert, ugly face like a little imp.
In John Milesius any man may reade
Of divels in Sarmatia honored
Call'd Kottri or Kibaldi ; such as wee
Pugs and hobgoblins call. Their dwellings bee
In corners of old houses least frequented,
Or beneath stacks of wood ; and these convented
Make fearfull noise in buttries and in dairies,
Robin good-fellowes some, some call them fairies.
[Thomas Heywood, "Hierarchie of the Blessed Angells," 1635]
The word, or identical words, at various times also meant "a husk of grain" (mid-15c.), "a bargeman" (1590s), "a harlot" (c. 1600), and "an upper servant in a great house" (1843), the last, if it is authentic, perhaps with a suggestion of "lap dog."
"I've seen him, father," said Nelly with a consequential air, "the day I was up at Fairfield Court; he came into Pug's Hole while the old lady was talking to me." For the benefit of the unlearned it should be mentioned that the under-servants "in respectable families" call upper-servants "Pugs;" and that the housekeeper's room is designated as "Pug's Hole." [F.E. Paget, "Warden of Berkingholt," 1843]