Trying to find opposite word for being efficacious in English? No problem. Our site contains antonyms of being efficacious in 21 different contexts. We have listed all the opposite words for being efficacious alphabetically.
PastTenses is a database of English verbs. One can check verbs forms in different tenses. Use our search box to check present tense, present participle tense, past tense and past participle tense of desired verb.