(1) a derrogatory term for someone that is disabled or has a medicial problem that results in physical impairment.

(2) An insult implying that someone is incompetent, stupid, etc. Can also be used to imply that the person is uncool or can't/won't do what everyone else is doing.

(3) A BDSM enthusiast who fancies full-bodied latex and or leather "gimp suits" for the purpose of movement disabling and sensory deprivation.

For the GNU Image Manipulation Program, which uses GIMP as an acronym, see gimp (software) and gimp (artwork).