The alliterative phrase kith and kin (late 14c.) originally meant "country and kinsfolk" and is almost the word's only survival in Modern English. Some cognates have evolved different senses, such as Dutch kunde "skill, competence," German Kunde "knowledge, news, tidings."
"knowing, wise," 1630s, from a Scottish and northern English formation from can (v.1) in its sense of "know how to," + -y (2). A doublet of cunning that flowered into distinct senses in Scottish English. In the glossary to Scott's "Heart of Mid-Lothian" (1818) uncanny is defined as "dangerous," while canny, as used in the tale, is defined as "skilful, prudent, lucky ; in a superstitious sense, good-conditioned, and safe to deal with ; trustworthy ; quiet." Cannily is "gently" and canny moment is "an opportune or happy time."
"Knowing," hence, from 18c., "careful, skillful, clever," also "frugal, thrifty," and, from early 19c. (perhaps via Scott's novels) "cautious, wary, shrewd." Often used superciliously of Scots by their southern neighbors (and their American cousins).
The Canny Scot is so well known as scarcely to require description. He carries caution, cunning, and selfishness to excess. Deceitful when a purpose is to be accomplished, he is not habitually deceitful. One thing he never loses sight of—his own interest. But of his own interest he is not the most enlightened judge. ["The Natural History of Scotsmen," in The Argosy, December 1865]
Related: Cannily; canniness.
c. 1200, kene, from Old English cene "bold, brave, fearless," in later Old English "clever, prudent, wise, intelligent," common Germanic (cognate with Old Norse kænn "skillful, wise," Middle Dutch coene "bold," Dutch koen, Old High German kuon "pugnacious, strong," German kühn "bold, daring"), but according to OED there are no cognates outside Germanic and the original meaning is "somewhat obscure"; it seem to have been both "brave" and "skilled." Perhaps the connection notion was "to be able" and the word is connected to the source of can (v.1).
Sense of "eager (to do something), vehement, ardent" is from c. 1300. The physical meaning "sharp, sharp-pointed, sharp-edged" (c. 1200) is peculiar to English. Extended senses from c. 1300: Of sounds, "loud, shrill;" of cold, fire, wind, etc. "biting, bitter, cutting." Of eyesight c. 1720. A popular word of approval in teenager and student slang from c. 1900. Keener was 19c. U.S. Western slang for a person considered sharp or shrewd in bargaining.
Old English agan (past tense ahte) "to have, to own," from Proto-Germanic *aiganan "to possess" (source also of Old Frisian aga "have to, ought to," Old Norse eiga, Old High German eigan, Gothic aigan "to possess, have"), from PIE root *aik- "be master of, possess."
The original sense is obsolete. The meaning "to have to repay, be indebted for" began in late Old English with the phrase agan to geldanne literally "to own to yield," which was used to translate Latin debere (earlier in Old English this would have been sceal "shall"); by late 12c. the phrase had been shortened to simply agan, and own (v.) took over this word's original sense.
The intransitive meaning "be in debt" is from mid-15c. To be owing to "be due or attributable to" is by 1650s.