A disability or handicap was a type of impairment of one's mind or body.
In 2364, while under the control of the Beta Renner cloud, Jean-Luc Picard tendered his resignation from command of the USS Enterprise-D and Starfleet, with the intention of leaving the starship and beam into the cloud. Doctor Beverly Crusher then relieved him from duty, giving his being "disabled and mentally incapacitated" as reasons. (TNG: "Lonely Among Us")
A common belief was that those who lost one ability compensated by increasing their other abilities. When Picard tried to discourage an non-empathic Deanna Troi from resigning her position by reminding her of this in 2367, she said it was a false belief probably created by normal people who felt uncomfortable around disabled ones. Picard started to tell her about a female teacher he had at the Academy who was a wheelchair user since birth, but she dismissed his "inspirational anecdote". (TNG: "The Loss")
In 2373, Julian Bashir told an injured, reckless Martok that he should accept the fact that he had a disability after the one-eyed Klingon foolishly turned off the holodeck safety protocols during a battle simulation. (DS9: "Soldiers of the Empire ")
- Birth defect
- Brain damage
- Memory loss
- Missing appendages