It has three definitions:

1. Shorthand term for Thirty Times (when one say triple it means three times thus a Thriple is thirty times)

2. Third Nipple

3. The name of the color in between the Red and the Magenta color spectrum. Lies more on the Violet / Purple side.

Internet persona(s) who happens to follow you and you happen to follow them back and maintain communication with and have a mutual liking for eachother whether it be friendship wise, etc. (Mutuals if more than one mutual)