Online Etymology Dictionary

uncouth: O.E. uncuð "unknown, uncertain, unfamiliar," from un- (1) "not" + cuð "known, well-known," pp. of cunnan "to know" (see can (v.)). Meaning "strange, crude, clumsy" is first recorded 1513. The compound (and the thing it describes) widespread in IE languages, cf. L. ignorantem,, O.N. ukuðr, Goth. unkunþs, Skt. ajnatah, Armenian ancanaut', Gk. agnotos, O.Ir. ingnad "unknown."
can (v.): O.E. 1st & 3rd pers. sing. pres. indic. of cunnan "know, have power to, be able," (also "to have carnal knowledge"), from P.Gmc. *kunnan "to be mentally able, to have learned" (cf. O.N. kenna "to know, make known," O.Fris. kanna "to recognize, admit," Ger. kennen "to know," Goth. kannjan "to make known"), from PIE base *gno- (see know). Absorbing the third sense of "to know," that of "to know how to do something" (in addition to "to know as a fact" and "to be acquainted with" something or someone). An O.E. preterite-present verb, its original p.p., couth, survives only in its negation (see uncouth), but cf. could. The prp. has spun off as cunning.
ignorant: late 14c., from O.Fr. ignorant, from L. ignorantia, from ignorantem, prp. of ignorare from in- "not" + Old L. gnarus "aware, acquainted with," from Porot-L. suffixed form *gno-ro-, related to gnoscere "to know" (see know). Form influenced by ignotus "unknown." Cf. also uncouth. Colloquial sense of "ill-mannered" first attested 1886.
bear (n.): O.E. bera "bear," from P.Gmc. *beron "the brown one" (cf. O.N. björn, Ger. Bär), from PIE *bher- (3) "bright, brown" (see brown). Greek arktos and Latin ursus retain the PIE root word for "bear" (*rtko), but it is believed to have been ritually replaced in the northern branches because of hunters' taboo on names of wild animals (cf. the Ir. equivalent "the good calf," Welsh "honey-pig," Lith. "the licker," Rus. 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 uncouth persons since 1570s. 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.
couth: O.E. cuðe "known," pp. of cunnan (see can (v.)) died out as such 16c., but the word was reborn 1896, with a new sense of "cultured, refined," as a back-formation from uncouth (q.v.). The O.E. word forms the first element in the man's proper name Cuthbert, lit. "famous-bright."