Eureka is an interjection that means "I found" or "discovered", exclamation made world famous by Archimedes of Syracuse.
It is usually pronounced by someone who has just find the solution to a difficult problem.
The term has its etymological origin in the Greek word “heureka”, the perfect past tense of the verb “heuriskein” which means “to find” or “to discover”.
The word "eureka” was supposedly pronounced by the Greek scientist Archimedes (287 BC Ç. – 212 a. C.), when he discovered how to solve a complex dilemma presented by King Hieron.
The king wanted to know if a crown ordered from the goldsmith was pure gold or if there was some other inferior material in its composition.
Archimedes knew that to do this he would have to determine the density of the crown and compare it with the density of the gold. The tricky problem was how to measure the volume of the crown without melting it.
Archimedes discovered the solution when he entered a bathtub of water and observed that the water level rose when he entered.
He then concluded that to measure the volume of the crown it was enough to immerse the crown in water and calculate the volume of water displaced, which should be equivalent.
It is said that he left, still naked, running through the streets and shouting euphoric: “Eureka! Eureka!” (I found! I found!). "The Principle of Archimedes" that was how the discovery of the great Greek scientist became known.