WordWeb Online

1. Poorly balanced or matched in quantity or value or measure
   - one-sided
    
2. Lacking the requisite qualities or resources to meet a task
   "she was unequal to the task"
   - inadequate

See also: adequacy, adequateness, anisometric, deficient, equality, incapable, incommensurate, incompetent, lacking, mismatched, nonequivalent, odds-on, short-handed, short-staffed, unbalanced, undermanned, understaffed, unequal to, unequalised [Brit], unequalized, unequally, uneven, unsatisfactory, unsymmetrical, wanting

Antonym: equal