efficacious (adj.)

• able
• active
• adequate
• authoritative
• capable
• charismatic
• charming
• competent
• consequential
• effective
• effectual
• efficient
• enchanting
• estimable
• functional
• go
• important
• influential
• magnetic
• momentous
• operational
• operative
• personable
• persuasive
• potent
• powerful
• practical
• prestigious
• productive
• proficient
• puissant
• reputable
• serviceable
• strong
• suasive
• substantial
• successful
• telling
• useful
• virtuous
• weighty
• winning