grouse (n.) Look up grouse at Dictionary.com
"bird," 1531, grows (pl., used collectively), of unknown origin, possibly from Latin or Welsh.
grouse (v.) Look up grouse at Dictionary.com
"complain," 1887, British Army slang (first recorded by Kipling), of uncertain origin but perhaps from Norman Fr. dial. groucer, from O.Fr. groucier "to murmur, grumble," of imitative origin (cf. Gk. gru "a grunt," gruzein "to grumble").