kith and kin

Kith is obsolete except in the alliterative phrase kith and kin, which originally meant "native land and people” and first appeared about 1377 in Piers Plowman. Kith comes from the Old English noun cȳth, "knowledge; known, familiar country; acquaintances, friends.” Cȳth in turn comes from the Germanic noun *kunthithō, a derivative of *kunthaz, "known.” Germanic *kunthaz was the past participle of a verb *kunnan, "to know, know how,” which became cunnan in Old English. The first person singular of this verb, can, is alive and well today, as is what was originally the verbal noun and adjective of cunnan, namely cunning, first appearing in the 14th century. Germanic *kunthaz itself survived in the Old English adjective cūth, "known, familiar,” a word that became obsolete in southern English by 1600, but has survived in its negative, uncouth. Modern English couth is actually a jocular back-formation introduced by Max Beerbohm in 1896.