From Old English 'bula,' from Proto-Germanic *bulô, possibly from PIE *bhel- (to swell) — named for the animal's powerful build.
From Old English 'bula' meaning 'bull, steer,' from Proto-Germanic *bulô, possibly from PIE *bhel- meaning 'to blow, swell,' referring to the animal's swollen, powerful build. Key roots: *bhel- (PIE: "to blow, swell").