bi ‧ cep /ˈbaɪsep/ BrE AmE noun [countable usually plural]
[ Date: 1600-1700 ; Language: Modern Latin ; Origin: biceps , from Latin , 'two-headed' , from caput 'head' ; because it is attached in two places ]
the large muscle on the front of your upper arm:
He had an eagle tattoo on one of his biceps.