There are 2 main definitions of eureka in English:

eureka1

Syllabification: eu·re·ka
Pronunciation: /yo͝oˈrēkə, yə-
 
/

exclamation

A cry of joy or satisfaction when one finds or discovers something.
More example sentences
  • There's nothing like the eureka moment of discovering something that no one knew before.
  • The samples were also chemically analyzed, and - eureka!
  • A few minutes later, as his story goes, he glanced at his full bookshelf and eureka!
Synonyms
bingo, I've got it, that's it

Origin

early 17th century: from Greek heurēka 'I have found it' (from heuriskein 'find'), said to have been uttered by Archimedes when he hit upon a method of determining the purity of gold. The noun dates from the early 20th century.

Definition of eureka in:

There are 2 main definitions of eureka in English:

Eureka2

Syllabification: Eu·re·ka
Pronunciation: /yo͝oˈrēkə, yə-
 
/
A port city in northwestern California, on Humboldt Bay off the Pacific Ocean, a noted lumbering center; population 25,300 (est. 2008).