empiric
empirical
nonsubjective
objective
absolute
actual
admitting no question
apodictic
attestable
authenticatable
checkable
confirmable
demonstrable
demonstratable
evincible
factual
historical
inappealable
incontestable
incontrovertible
indisputable
indubitable
irrefragable
irrefutable
provable
real
self-evident
substantiatable
supportable
sustainable
testable
unanswerable
unconfutable
undeniable
unimpeachable
unquestionable
unrefutable
validatable
achievable
apprehensible
ascertainable
communicable
concealable
corroborative
credible
definable
explicable
implausible
intelligible
meaningful
measurable
observable
quantifiable
realisable
rock-solid
traceable
valid
falsifiable