adjective
- not efficient; unable to effect or achieve the desired result with reasonable economy of means.
- lacking in ability, incompetent.
adjective
- unable to perform a task or function to the best advantage; wasteful or incompetent
- unable to produce the desired result
1750, “not producing the desired effect,” from in- (1) “not, opposite of” + efficient. Related: Inefficiency (1749); inefficiently.