Useless is another word for ineffective. Additional synonyms include inadequate, powerless, futile and unproductive.
Feckless
Cause.
It is ineffectual (not inaffectual), and it means ineffective.
If you mean "ineffective", that means it's not effective.
Superb is another word for excellent. Superb is another word for excellent.
Feckless
ineffective, in vain, ineffectual, useless, futile.
an ineffective can was lurking around the park last Monday.
Cause.
We all knew that the assembly would be ineffective in preventing underage drinking.
ineffective, ineffectual, unable, impuissant, Impotent
It is ineffectual (not inaffectual), and it means ineffective.
feckless
Forceless or Failing
Words meaning to cancel or make ineffective are void, revoke, annul, counteract, offset, invalidate...
If you mean "ineffective", that means it's not effective.
Ineffective