beef (n.) Look up beef at Dictionary.com
c.1300, from Old French buef "ox; beef; ox hide" (11c., Modern French boeuf), from Latin bovem (nominative bos, genitive bovis) "ox, cow," from PIE root *gwou- "cow, ox, bull" (see cow (n.)). Original plural was beeves.
beef (v.) Look up beef at Dictionary.com
"to complain," slang, 1888, American English, from noun meaning "complaint" (1880s). The noun meaning "argument" is recorded from 1930s. The origin and signification are unclear; perhaps it traces to the common late 19c. complaint of U.S. soldiers about the quantity or quality of beef rations.