Lacking or deficient in the proper or desired quality; of little excellence or worth; of a low or inferior standard or quality. See also sense A. 4.

Having a defect or defects; lacking a required or necessary quality; deficient; imperfect; faulty.

Lacking some quality or attribute necessary to perfection; less than perfect in quality or condition; substandard, flawed; defective, faulty.

As past participle: destitute, devoid.

As past participle: deprived of something.

Imperfect, defective.

Usually in predicative use. Defective, spoilt; missing, lacking.