gator

The word 'gator' is a modern American English colloquial clipping of 'alligator'. 'Alligator' itself entered English via Spanish 'el lagarto' (the lizard), which was a modification of the Latin 'lacertus' or 'lacerta', meaning lizard. The Spanish term was applied to the large reptiles encountered in the Americas. The clipped form 'gator' emerged as a convenient, informal term, reflecting a common linguistic process where longer words are shortened in casual speech, especially for familiar fauna in regions like the southeastern United States.

This is a clipped form, not a compound or derivation from separate morphemes. It is a direct shortening of the English word 'alligator'.