You searched for: “deficient
defective, deficient
defective (di FEK tiv) (adjective)
Referring to something which is missing an element that is essential or critical for functioning properly: Bert had to return his vacuum cleaner to the store where he bought it because it was defective.
deficient (di FISH uhnt) (adjective)
Not up to typical expectations or standards; lacking in essential elements: The doctor stated that the tests indicated Chelsea was deficient in iron and needed to take a supplement.

Ethan noticed the defective valve in the engine. This is definitely deficient in terms of what he had expected from the manufacturer.

A unit related to: “deficient
(Greek: under, below, beneath; less than; too little; deficient, diminished; used as a prefix)