ef ‧ fec ‧ tu ‧ al /ɪˈfektʃuəl/ BrE AmE adjective formal
[ Word Family: noun : ↑ effect , ↑ effectiveness ≠ ↑ ineffectiveness ; adjective : ↑ effective ≠ ↑ ineffective , ↑ effectual ≠ ↑ ineffectual ; verb : ↑ effect ; adverb : ↑ effectively ≠ ↑ ineffectively ]
producing the result that was wanted or intended SYN effective OPP ineffectual