Meaning of “ineffective” - Learner’s Dictionary

ineffective

adjective uk us /ˌɪnɪˈfektɪv/

If something is ineffective, it does not work well:

Morphine is used only when other painkillers are ineffective.
ineffectively adverb
ineffectiveness noun [ U ]

(Definition of “ineffective” from the Cambridge Learner’s Dictionary © Cambridge University Press)