1. Marked by qualities giving the power to produce an intended effect
   "written propaganda is less efficacious than the habits and prejudices...of the readers"; "the medicine is efficacious in stopping a cough" 
2. Producing or capable of producing an intended result or having a striking effect
   "an efficacious law"
   - effective, effectual

See also: effective, effectiveness, effectivity, effectuality, effectualness, efficaciously, efficaciousness, efficacy, efficient, hard-hitting, impelling, impressive, potent, powerful, rough-and-ready, stiff, strong, telling, trenchant, useful, utile

Antonym: inefficacious

Encyclopedia: Efficacious

• dowel
• dowel pin
• doweling
• dowelling
• dower
• dowered
• dowerless
• dowery
• dowitcher
• Dowland
• down
• Down Easter
• down feather
• down in the mouth
• down pat
• down payment
• down quark
• Down syndrome
• down the road
• down the stairs
• down under
• Down's syndrome
• down-and-out
• down-at-heel
• down-at-the-heel