Real Dictionary

aye aye in British English
an expression of compliance, esp used by seamen
I understand and will obey
noun: a rare nocturnal arboreal prosimian primate of Madagascar, Daubentonia madagascariensis, related to the lemurs: family Daubentoniidae. It has long bony fingers and rodent-like incisor teeth adapted for feeding on insect larvae and bamboo pith

aye-aye in American English
an arboreal, nocturnal prosimian primate (Daubentonia madagascariensis) of Madagascar, with shaggy, generally dark-brown fur, large ears, fingerlike claws, and a long, bushy tail
noun: a nocturnal lemur, Daubentonia madagascariensis, of Madagascar, feeding on insects and fruit, and having rodentlike incisors and long fingers: an endangered species