(verb) (1) When snowboarding, to undo one's bindings (also un-strap)
(2) After crossplaying, to take off the tape or ace bandages (see binding) that is holding down your boobs. Painful at first (especially with tape) but very much worth it later.
(1) "Man, I was snowboarding for so long, when I un-bound, it felt so weird to move my legs individually!"
(2) "Oh god, anime conventions really tire me out. Time to go home and un-bind."