Open English Wordnet
Adjectives
(a)ineffective, uneffective, ineffectualnot producing an intended effect“an ineffective teacher”, “ineffective legislation”
(s)ineffective, ineffectual, unablelacking in power or forcefulness“an ineffectual ruler”, “like an unable phoenix in hot ashes”
(s)ineffective, inefficientlacking the ability or skill to perform effectively; inadequate“an ineffective administration”, “inefficient workers”