Thank you for the comments, everyone.
does the name have anything to do with godzilla
No, not at all. But come to think of it, they do sound awfully similar.
There is a map on UT2k4 called "Rrajigar." I took that name and scrambled the letters around, like it's some anagram game. I got alot of neat-sounding words, but "Gajira" sounded the most appealing to me. I added another A to the end to make it sound more alien and that's how I got the name.
Rejected names include "Jigarra," "Girar," and "Jarira."