Efficacious

/ˌɛf.ɪˈkeɪ.ʃəs/

Antonyms for "efficacious" (7 found)

Adjective(7 words)

inadequate ineffective inefficacious insufficient unproductive unproven useless

More for "efficacious"

Meaning Synonyms

Keep exploring

Expand with synonyms Read the definition Writing guides