what is APE stands for? Where i can find the specification document for APE (monkey's audio)? is there any link i can get the source code otherthan www.monkeysaudio.com? please let me know, and sorry for asking basic doubts.

the source code from monkeysaudio.com is the only original SC. why do you have doubts on this codec?
Monkey's Audio is a lossless codec, further definition and details can be read at monkeysaudio.com.
APE is just the file extention name for Monkey's Audio files (*.ape).
It WAS one of the first wide-spreaded codecs in lossless use. Nowadays FLAC, WavPack and ALAC are used by more people than APE.

Methinks it was just a cheeky, primate-related choice of a three letter extension!

A monkey is generally referred to as an ape

Sorry to be pedantic - and OT - but while monkeys and apes are both primates they are completely different "branches" of the primate tree and are not the same thing at all. The most obvious difference being that monkeys have tails while apes don't.

Thank you for your replies.
Does monkey's audio has the spcification document, if yes can you point me where i can get it?
I didn't find any specification document in the monkeysaudio.com.

Evidently you didn't look hard enough: http://monkeysaudio.com/developers.html