Since I arrived late to the party, I think I first discovered this tidbit in the Wiki article, which I believe explains it pretty well:
in reply to Re^4: Developer::Perl::Find
in thread Developer::Perl::Find
Perl was originally named "Pearl", after "the pearl of great price" of Matthew 13:46. Larry Wall wanted to give the language a short name with positive connotations, and claims he looked at (and rejected) every three- and four-letter word in the dictionary. He even thought of naming it after his wife Gloria. Before the language's official release, Wall discovered that there was already a programming language named Pearl, and changed the spelling of the name.
I downloaded Version 1.0 to look at the man page, and lo and behold, the "old"|"new" name was still there:
perl - Practical Extraction and Report Language, so I don't think that this could really be considered a post-facto expansion (so long as we would consider v1.0 the first real Perl "event", so to speak - if we didn't, we would need to search deep within the bountiful caverns of Larry Wall's mind for guidance, during the time that the primordial ooze was congealing). Consistent with the current man pages, the 'a' is in lower-case while the other initial letters are in upper-case, suggesting (but not saying) that someone once thought of this as an acronymic representation of something (perl|pearl), notwithstanding the fact that it was created independently and after the assignment of the name Perl.
Impossible! The Remonster can only be killed by stabbing him in the heart with the ancient bone saber of Zumakalis!