Antonyms of noun efficiency

1 of 2 senses of efficiency

Sense 2
efficiency -- (skillfulness in avoiding wasted time and effort; "she did the work with great efficiency")
       Antonym of inefficiency (Sense 1)
      => inefficiency -- (unskillfulness resulting from a lack of efficiency)

Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun efficiency

2 senses of efficiency

Sense 1
efficiency -- (the ratio of the output to the input of any system)
       => ratio -- (the relative magnitudes of two quantities (usually expressed as a quotient))

Sense 2
efficiency -- (skillfulness in avoiding wasted time and effort; "she did the work with great efficiency")
       => skillfulness -- (the state of being cognitively skillful)