yak (n.) Look up yak at Dictionary.com
"wild ox of central Asia," 1795, from Tibetan g-yag "male yak." Attested in French from 1791.
yak (v.) Look up yak at Dictionary.com
"laugh," 1938, variant of yuck (2); "talk idly," 1950, variant of yack. Related: Yakked; yakking.