37 synonyms for disadvantage such as handicap, catch, be unfair to, and do a disservice to. Disadvantage is a noun, and its antonyms are advantage and benefit.
Catch, complication, defect, difficulty, disbenefit, downside, drawback, fault, flaw, fly in the ointment, handicap, hiccup, hindrance, impediment, liability, limitation, minus, monkey wrench in the works, nuisance, obstacle, pitfall, problem, snag, spanner in the works, stumbling block, trouble, weak spot/point, and weakness.
Be unfair to, do a disservice to, handicap, inflict a handicap on, put at a disadvantage, treat harshly/unfairly, treat unfavourably, and wrong.