Breadcrumb Home > Thesaurus > I Synonyms of inefficacious Find synonyms for: Adjective 1. inefficacious (vs. efficacious), ineffective#1, uneffective#1, ineffectual usage: lacking the power to produce a desired effect; "laws that are inefficacious in stopping crime" WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of inefficacious (Dictionary) TrendingHere are the facts and trivia that people are buzzing about. Chinese New Year History, Meaning, and Celebrations Current Events This Week: February 2024 Valentine's Day Valentine's Day History Mardi Gras 30 "Charlie and the Chocolate Factory" Quotes ✖ Related Content Daily Word Quiz: irascible Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language