Antonyms of adj efficient

2 senses of efficient

Sense 1
efficient (vs. inefficient) -- (being effective without wasting time or effort or expense; "an efficient production manager"; "efficient engines save gas")

inefficient (vs. efficient) -- (not producing desired results; wasteful; "an inefficient campaign against drugs"; "outdated and inefficient design and methods")
        => uneconomical, wasteful -- (inefficient in use of time and effort and materials; "a clumsy and wasteful process"; "wasteful duplication of effort"; "uneconomical ebb and flow of power")

Sense 2
effective, efficient -- (able to accomplish a purpose; functioning effectively; "people who will do nothing unless they get something out of it for themselves are often highly effective persons..."-G.B.Shaw; "effective personnel"; "an efficient secretary"; "the efficient cause of the revolution")

INDIRECT (VIA competent) -> incompetent -- (not qualified or suited for a purpose; "an incompetent secret service"; "the filming was hopeless incompetent")

Similarity of adj efficient

2 senses of efficient

Sense 1
efficient (vs. inefficient) -- (being effective without wasting time or effort or expense; "an efficient production manager"; "efficient engines save gas")
       => businesslike -- (exhibiting methodical and systematic characteristics that would be useful in business)
       => cost-efficient, cost-effective -- (productive relative to the cost)
       => economic, economical -- (using the minimum of time or resources necessary for effectiveness; "an economic use of home heating oil"; "a modern economical heating system"; "an economical use of her time")
       => expeditious -- (marked by speed and efficiency)
       => high-octane -- (used of gasoline; having a high octane number)
       => streamlined -- (made efficient by stripping off nonessentials; "short streamlined meetings"; "a streamlined hiring process")
          Also See-> competent#1; effective#1, effectual#1, efficacious#2

Sense 2
effective, efficient -- (able to accomplish a purpose; functioning effectively; "people who will do nothing unless they get something out of it for themselves are often highly effective persons..."-G.B.Shaw; "effective personnel"; "an efficient secretary"; "the efficient cause of the revolution")
       => competent (vs. incompetent) -- (properly or sufficiently qualified or capable or efficient; "a competent typist")