Meaning of INEFFECTIVE in English

INEFFECTIVE

in ‧ ef ‧ fec ‧ tive /ˌɪnəˈfektɪv◂, ˌɪnɪˈfektɪv◂/ BrE AmE adjective

[ Word Family: noun : ↑ effect , ↑ effectiveness ≠ ↑ ineffectiveness ; adjective : ↑ effective ≠ ↑ ineffective , ↑ effectual ≠ ↑ ineffectual ; verb : ↑ effect ; adverb : ↑ effectively ≠ ↑ ineffectively ]

something that is ineffective does not achieve what it is intended to achieve OPP effective

ineffective in doing something

The chemical was almost totally ineffective in killing the weeds.

ineffective against

Various drugs have proved ineffective against the virus.

an ineffective marketing campaign

—ineffectively adverb

—ineffectiveness noun [uncountable] :

the ineffectiveness of most diets

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In everyday English, people usually say that something does not work rather than saying that it is ineffective :

These drugs don’t work against bird flu.

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.