bugbear (n.)

"insect, beetle," 1620s (earliest reference is to bedbugs), of unknown origin, probably (but not certainly) from or influenced by Middle English bugge "something frightening, scarecrow" (late 14c.), a meaning obsolete since the "insect" sense arose except in bugbear (1570s) and bugaboo (q.v.).

Probably connected with Scottish bogill "goblin, bugbear," or obsolete Welsh bwg "ghost, goblin" (compare Welsh bwgwl "threat," earlier "fear," Middle Irish bocanách "supernatural being"). Some speculate that these words are from a root meaning "goat" (see buck (n.1)) and represent originally a goat-like spectre. Compare also bogey (n.1) and Puck. Middle English Compendium compares Low German bögge, böggel-mann "goblin." Perhaps influenced in meaning by Old English -budda used in compounds for "beetle" (compare Low German budde "louse, grub," Middle Low German buddech "thick, swollen").

The name of bug is given in a secondary sense to insects considered as an object of disgust and horror, and in modern English is appropriated to the noisome inhabitants of our beds, but in America is used as the general appellation of the beetle tribe .... A similar application of the word signifying an object dread to creeping things is very common. [Hensleigh Wedgwood, "A Dictionary of English Etymology," 1859]

Meaning "defect in a machine" (1889) may have been coined c. 1878 by Thomas Edison (perhaps with the notion of an insect getting into the works). Meaning "person obsessed by an idea" (as in firebug "arsonist") is from 1841, perhaps from notion of persistence. Sense of "microbe, germ" is from 1919. Bugs "crazy" is from c. 1900. Bug juice as a slang name for drink is from 1869, originally "bad whiskey." The 1811 slang dictionary has bug-hunter "an upholsterer." Bug-word "word or words meant to irritate and vex" is from 1560s.

"large carnivorous or omnivorous mammal of the family Ursidae," Old English bera "a bear," from Proto-Germanic *bero, literally "the brown (one)" (source also of Old Norse björn, Middle Dutch bere, Dutch beer, Old High German bero, German Bär), usually said to be from PIE root *bher- (2) "bright; brown." There was perhaps a PIE *bheros "dark animal" (compare beaver (n.1) and Greek phrynos "toad," literally "the brown animal").

Greek arktos and Latin ursus retain the PIE root word for "bear" (*rtko; see arctic), but it is believed to have been ritually replaced in the northern branches because of hunters' taboo on names of wild animals (compare the Irish equivalent "the good calf," Welsh "honey-pig," Lithuanian "the licker," Russian medved "honey-eater"). Others connect the Germanic word with Latin ferus "wild," as if it meant "the wild animal (par excellence) of the northern woods."

Symbolic of Russia since 1794. Used of rude, gruff, uncouth men since 1570s. Stock market meaning "speculator for a fall" is 1709 shortening of bearskin jobber (from the proverb sell the bearskin before one has caught the bear); i.e. "one who sells stock for future delivery, expecting that meanwhile prices will fall." Paired with bull from c. 1720. Bear claw as a type of large pastry is from 1942, originally chiefly western U.S. Bear-garden (1590s) was a place where bears were kept for the amusement of spectators.