Handicap is a noun meaning (1) an advantage or penalty imposed to make a race or contest fair, (2) a hindrance, and (3) a physical or mental disability. It’s also a verb meaning (1) to assign handicaps, and (2) to impede. For describing a person or group, handicapped is the grammatically correct word.
But, grammar aside, both handicap and handicapped have fallen out of favor in all uses relating to physical and mental disabilities. Handicapped is not as offensive as some euphemisms, but it is considered inferior to words like disabled and impaired.
Examples
Most instances of handicap have nothing to do with disability—for example:
He was bidding for a hat-trick in a 12-furlong handicap at Newmarket last October but failed to get home in soft ground. [Mirror]
[H]er personal transparency has been a professional boon instead of a handicap. [Forbes]
Whatever may handicap the U.S. economy (such as excess government spending), manufacturing isn’t it. [Globe and Mail]
And although handicapped is not as good as some of the alternatives, it is not necessarily offensive and does appear in edited publications—for example:
The third school was for handicapped and deaf children. [Miami Herald]
He met Lorna May Criddle, an art teacher working with handicapped children, at a dance in Norwich in the summer of 1939. [Sydney Morning Herald]
Thieves are targeting the vehicles of handicapped drivers in Metro Vancouver … [Vancouver Sun]
Terms like handicapped parking and handicap-accessible are grammatically questionable, but they’re so widespread in disability-related terminology that we have to accept them.
