Close-up Photo Of An American Alligator

The form crocodrillus is attested in Medieval Latin. It is not clear whether this is a medieval corruption or derives from alternate Greco-Latin forms (late Greek corcodrillos and corcodrillion are attested).
A (further) corrupted form cocodrille is found in Old French and was borrowed into Middle English as cocodril(le). The Modern English form crocodile was adapted directly from the Classical Latin crocodīlus in the 16th Century, replacing the earlier form.
The use of -y- in the scientific name Crocodylus (and forms derived from it) is a corruption introduced by Laurenti (1768).