Efficient

Antonyms of EFFICIENT

abortive, inexperienced, lazy, powerless, unqualified, inexpert, inefficient, fragile, inadequate, inept, incompetent, delicate, unable, sluggish, weak, inactive, empty, hollow, unfruitful, inoperative, useless, vain, bootless, worthless, helpless, impotent, incapable, ineffective, unseasoned, idle, unskillful, pointless, unskilled.