Eureka (word)
"Eureka" comes from the Ancient Greek word "heúrēka", meaning "I found (it)", which is the first person singular perfect indicative active of the verb "heuriskō" "I find". It is closely related to heuristic, which refers to experience-based techniques for problem solving, learning, and discovery.
Yekke
Another theory is that the word derives from "Yekkef", the Western European pronunciation of the name "Jacob" or "Jack", which differs from the Eastern European pronunciation, "Yankef" or "Yankev" (also see German "Jäckel", pronounced "yekkel", the German diminutive form of Jakob).