"predicament," 1580s, from Middle English lurch (v.) "to beat in a game of skill (often by a great many points)," mid-14c. (implied in lurching), probably literally "to make a complete victory in lorche," an old game akin to backgammon, with a name of uncertain origin. Perhaps it is related to Middle English lurken, lorken "to lie hidden, lie in ambush" (Middle English Compendium; see lurk), or it may be from Old French lourche, from Middle High German lurz "left," also "wrong" [OED]. The immediate source of the transferred use in leave in the lurch "leave suddenly and unexpectedly in an embarrassing predicament" (1590s) would be cribbage.
The Dutch word is said to be cognate with Old English lutian "lurk," and related to Old English loddere "beggar;" Old High German lotar "empty, vain," luzen "lurk;" German Lotterbube "vagabond, rascal," lauschen "eavesdrop;" Gothic luton "mislead;" Old English lyðre "base, bad, wicked." Related: Loitered; loitering.
"slice or small bulb forming together a large bulb, as of garlic," Old English clufu "clove (of garlic), bulb, tuber," from Proto-Germanic *klubo "cleft, thing cloven" (source also of Old High German chlobo, Old Norse klofi), from PIE root *gleubh- "to tear apart, cleave."
Its Germanic cognates mostly lurk in compounds that translate as "clove-leek," such as Old Saxon clufloc, Old High German chlobilouh. Dissimilation produced Dutch knoflook, German Knoblauch.
mid-15c., "concealed, secret," from Latin latentem (nominative latens) "lying hid, concealed, secret, unknown," present participle of latere "lie hidden, lurk, be concealed," from PIE *late-, suffixed form of root *lādh- "to be hidden" (source also of Greek lēthē "forgetfulness, oblivion," lēthargos "forgetful," lathre "secretly, by stealth," lathrios "stealthy," lanthanein "to be hidden;" Old Church Slavonic lajati "to lie in wait for"). Meaning "dormant, undeveloped" is from 1680s, originally in medicine.
1540s, "awkward fellow, boor, bumpkin," of uncertain origin. Perhaps a noun from a dialectal survival of Middle English louten (v.) "bow down" (c. 1300), from Old English lutan "bow low," from Proto-Germanic *lut- "to bow, bend, stoop" (source also of Old Norse lutr "stooping," which itself might also be the source of the modern English word).
According to Watkins this is from PIE *leud- "to lurk" (source also of Gothic luton "to deceive," Old English lot "deceit), also "to be small" (see little). Non-Germanic cognates probably include Lithuanian liūdėti "to mourn;" Old Church Slavonic luditi "to deceive," ludu "foolish." Sense of "cad" is first attested 1857 in British schoolboy slang.
Old English be- (unstressed) or bi (stressed) "near, in, by, during, about," from Proto-Germanic *bi "around, about," in compounds often merely intensive (source also of Old Saxon and Old Frisian bi "by, near," Middle Dutch bie, Dutch bij, German bei "by, at, near," Gothic bi "about"), from PIE *bhi, reduced form of root *ambhi- "around."
As an adverb by c. 1300, "near, close at hand." OED (2nd ed. print) has 38 distinct definitions of it as a preposition. Originally an adverbial particle of place, which sense survives in place names (Whitby, Grimsby, etc., also compare rudesby). Elliptical use for "secondary course" was in Old English (opposed to main, as in byway, also compare by-blow "illegitimate child," 1590s, Middle English loteby "a concubine," from obsolete lote "to lurk, lie hidden"). This also is the sense of the second by in the phrase by the by (1610s). By the way literally means "along the way" (c. 1200), hence "in passing by," used figuratively to introduce a tangential observation ("incidentally") by 1540s.
To swear by something or someone is in Old English, perhaps originally "in the presence of." Phrase by and by (early 14c.) originally meant "one by one," with by apparently denoting succession; modern sense of "before long" is from 1520s. By and large "in all its length and breadth" (1660s) originally was nautical, "sailing to the wind and off it," hence "in one direction then another;" from nautical expression large wind, one that crosses the ship's line in a favorable direction.