hard-hitting
impelling
impressive
rough-and-ready
telling
trenchant
valid
able
achieving
active
actual
adequate
ascertained
attested
authenticated
authoritative
banausic
behind the scenes
binding
capable
categorically true
causal
causative
certain
certified
charismatic
charming
competent
conclusive
confirmed
consequential
constitutive
corroborated
decisive
demonstrated
determinative
determined
documentary
effective
efficacious
efficient
enchanting
equal to
established
estimable
etiological
factual
feasible
forceful
forcible
formative
fulfilling
effect
effectivity
efficacity
efficacy
efficiency
drastic
economical
immediate
judicious
justifiable
needful
prudent
reasonable
salutary
speedy
ineffectual