Choose the perfect synonym or antonym for the word

Efficient

/ɪˈfɪʃənt/

Able to achieve maximum productivity with minimum wasted effort or expense.

Synonyms:

'Our police force has been very efficient in capturing the murderer.

The process proved efficient.

Anyway, he was there, swinging a dashed efficient shoe.

Originating from Latin efficere meaning work out or accomplish, it entered English through the Old French efficient in the late Middle Ages.

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