The Mors is an enemy in Final Fantasy IV -Interlude-. They are not very powerful enemies, and when left alone, will escape from battle. It is advised to defeat them first if given the chance.
Mors is the Latin word for "death". The enemy's name is most likely a mistransliteration of 'Molz', as its name in the Eastype version of Final Fantasy IV (exclusive to Japan) was 'Floating Mold'.