Eureka \Eu*re"ka\ [Gr. ? I have found, perfect indicative of ? to find.]

The exclamation attributed to Archimedes, who is said to have cried out ``Eureka! eureka!'' (I have found it! I have found it!), upon suddenly discovering a method of finding out how much the gold of King Hiero's crown had been alloyed. Hence, an expression of triumph concerning a discovery.

Source: Webster's Revised Unabridged Dictionary (1913)