A fair enough question. Unfortunately, the answer isn't so simple. The problem is, there are quite a few different systems of octave designation, and unless the person you are communicating with says which one they're using, calling a note double or triple, or whatever, is actually fairly useless. you'll hear people say "super" this, or "triple" that... and sometimes, they're not even using any real accepted system of octave designation at all. I have found that if you give whatever note in terms of its distance from middle C, most people will know what you're talking about. but, if you want to learn about the different systems (some of them, anyway.. there are others), you can check this site out.
http://www.music.vt.edu/musicdictionary/appendix/octaveregisters/octaveregisters.html
as you'll notice, none of these systems use "double" or "triple" at all. though you will hear double and triple used in terms of the extreme low pedal ranges.
for what it's worth, the military teaches yet another system, just to make things more confusing