bout (n.) Look up bout at Dictionary.com
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).
bout (adv., prep.) Look up bout at Dictionary.com
also 'bout, short for about, mid-13c.