Ar ‧ chi ‧ me ‧ des /ˌɑːkɪˈmiːdiːz◂ $ ˌɑːr-/ BrE AmE
(?287–212 BC) a Greek ↑ mathematician and inventor who discovered Archimedes’ Principle, the fact that when you put an object in a liquid, it seems to weigh less by a certain amount, and this amount is equal to the weight of the liquid which it has taken the place of. According to a well-known story, he discovered this while in the bath, and jumped out of the bath and ran through the streets shouting ‘Eureka!’ (=I have found it!)