efficacious

adj

Etymology: From Old French efficacieux, from Latin efficāx (“efficacious”) + -ous, from efficere (“to effect, to accomplish”); see effect.

1. Effective; possessing efficacy.

   “This medicine is efficacious.”

   “For, that the ordure, which continually gathers on the skin, would ſoon ſtop the pores of it, if the ſweat were not furniſht with ſome efficacious diſſolvent to open and pierce them.”