bout (n.)

1540s, "a roundabout way" (obsolete), from Middle English bught, probably from an unrecorded Old English variant of byht "a bend," from Proto-Germanic *bukhta- (see bight (n.)). Sense evolved from "a circuit of any kind" (as of a plow) to "a round at any kind of exercise" (1570s), "a round at fighting" (1590s), "a fit of drinking" (1660s), "a fit of illness" (by 1938).

also 'bout, short for about, mid-13c.