WordNet sense 1 (established irrevocably):

sealed

WordNet sense 2 (worthy of reliance or trust):

reliable

WordNet sense 3 (precise; explicit and clearly defined):

definite

WordNet sense 4 ((usually followed by `to') governed by fate):

bound, destined

WordNet sense 5 (persuaded of; very sure):

convinced, positive

WordNet sense 6 (impossible to doubt or dispute):

indisputable, sure

WordNet sense 7 (exercising caution or showing care or attention):

careful