reasonable
sensible
just
deep-rooted
erroneous
gravest
groundless
ill-concealed
ill-disguised
ill-founded
ill-suppressed
ineradicable
insurmountable
justifiable
long-standing
preconceived
unconquerable
undefined
undoubting
unreasoning
unshakable
unsubstantiated
unvoiced
weightier
well-grounded
unfounded