I don't think I saw an explanation for beef above. Here's what I found:

Online Etymology Dictionary
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.