Two options (click on the hyperlinks for meanings):
1) As Diana said, it's probably a variation of Taryn, which in turn is an elaboration of Tara.
2) It could be a contraction of Terri - Anne when on a girl, and an elaboration of Terry for a boy.
But my money is on a).
It probably isn't in our database simply because the site creator doesn't know which origin is correct - less common names don't get added to the site unless their origin can be fairly well established.