(n.) Lacking power or energy sufficient for the desired effect\; inefficacy; incapacity; as, he was discharged from his position for inefficiency.

disability disablement disqualification imbecility inability inadeptness inadequacy inaptitude inaptness inattentiveness incapability incapacitation incapacity incompetence incompetency indexterity ineffectiveness ineffectuality ineptitude ineptness infancy inferiority insufficiency legal incapacity maladjustment maladroitness mediocrity minority pedestrianism rustiness skill-lessness thoughtlessness unaptness uncleverness undeftness undexterousness undextrousness unfitness unfittedness unintelligence unproficiency unschooledness unskillfulness untrainedness wardship