seno
/ˈseno/ · B1 · noun · m
breast
seno = Latin sinus (curve, fold, bosom), the root of English sine and sinus
Latin sinus meant a curved fold, like the fold of a toga over the chest. Spanish kept it as seno for the bosom. English kept it as sinus, the hollow in the skull. Mathematicians used it for sine, after a mistranslation from Arabic.