Manisha means thought in Sanskrit, but the connotation is broad enough to include intellect, desire, wish, request, prayer, and hymn. The word does not contain the isha that means possesor/master. There are three sibilants in Sanskrit, this word contains the retroflex variety, not the palatal one that appears in possessor. So, `goddess of desire' is a doubtful meaning, and I do not remember the word being used with that meaning. (Manish, contrary to what appears on this site, is not Sanskrit; and since in many modern Indian languages the two sibilants are similar in sound, one can find multiple spellings for this name.)
The word is actually quite old, appearing in the Rgveda. The root manas is cognate with the roots of English words like mnemonic.