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know

O.E. cnawan (class VII strong verb; past tense cneow, pp. cnawen), from P.Gmc. *knoeanan (cf. O.H.G. bi-chnaan, ir-chnaan "to know"), from PIE base *gno- "to know" (cf. O.Pers. xšnasatiy "he shall know;" O.C.S. znati, Rus. znat "to know;" L. gnoscere; Gk. *gno-, as in gignoskein; Skt. jna- "know"). Once widespread in Germanic, this form is now retained only in English, where however it has widespread application, covering meanings that require two or more verbs in other languages (e.g. Ger. wissen, kennen, erkennen and in part können; Fr. connaître, savoir; L. novisse, cognoscire, scire; O.C.S. znaja, vemi). The Anglo-Saxons used two distinct words for this, witan (see wit) and cnawan. Meaning "to have sexual intercourse with" is attested from c.1200, from the O.T. To not know one's ass from one's elbow is from 1930. To know better "to have learned from experience" is from 1704. You know as a parenthetical filler is from 1712, but it has roots in 14c.

know-nothing

"ignoramus," 1827, from know + nothing. As a U.S. nativist political party, active 1853-56, the name refers to the secret society at the core of the party, about which members were instructed to answer, if asked about it, that they "know nothing." The party eventually merged into the Republican Party.

knowhow

also know-how, "technical expertise," 1838, Amer.Eng., from know + how.

knowingly

late 14c., from prp. of know + -ly (2).

knowledge

M.E. cnawlece. For first element see know. Second element obscure, perhaps cognate with the -lock "action, process," found in wedlock.

knowledgeable

also knowledgable, c.1600, "capable of being known, recognizable" (a sense now obsolete), from knowledge (which also was a verb in M.E.) + -able. The modern sense of "having knowledge, displaying knowledge" is from 1829 and probably a new formation.

acknowledge

1550s, a blend of M.E. aknow (from O.E. oncnawan "understand," from on + cnawan "recognize;" see know) and M.E. verb knowlechen "admit" (late 15c.). Somehow, in the merger, a parasitic -c- slipped in, so that, while the kn- became a simple "n" sound (as in know), the -c- stepped up to preserve, in this word, the ancient "kn-" sound. Related: Acknowledged; acknowledging.

acknowledgement

also acknowledgment ("a spelling more in accordance with Eng. values of letters" [OED]), 1590s, "act of acknowledging," from acknowledge + -ment. "An early instance of -ment added to an orig. Eng. vb." [OED]. Meaning "token of due recognition" is recorded from 1610s.

foreknowledge

1530s, from fore + knowledge.

unbeknown

1630s, from un- (1) “not” + beknown (see be- + pp. of know).

unbeknownst

1848, vulgar formation from unbeknown (1630s). No clear reason for the -st, but since 19c. this has become the dominant form.

unknowing

c.1300 (adj.) “without knowledge, ignorant,” from un- (1) “not” + prp. of know. Noun meaning “ignorance” is mid-14c. Related: Unknowingly.

unknown (adj.)

c.1300, "strange, unfamiliar" (of persons, places), from un- (1) "not" + pp. of know. Cf. O.E. ungecnawen. In ref. to facts, attested from early 14c. The noun meaning "unknown person" is recorded from 1590s.

well-known

late 15c., from well (adv.) + pp. of know.