JAGADISH, it means "The Lord of the Universe".
Jagatasya means "of the Universe" and isha means "The Lord" and according to Shashthi TatOurusha Samas Rules this becomes Jagat+Isha where the "ta" at the end of the first word becomes "da" and "i" (pronouced as E) at the begining of the second word joins to make it "di".
Alternatively according to the rules of Vyanjana Sandhi the two words Jagata and Isha are joined to make Jagadish.