WordNet sense 1 ((of persons) worthy of trust or confidence):

trusted

WordNet sense 2 (worthy of trust or belief):

trustworthy, trusty

WordNet sense 3 (not subject to change or variation especially in behavior):

steady

WordNet sense 4 (free from danger or risk):

secure

WordNet sense 5 (worthy of reliance or trust):

reliable

WordNet sense 6 ((usually followed by `to') governed by fate):

bound

WordNet sense 7 (persuaded of; very sure):

confident, convinced, positive

WordNet sense 8 (impossible to doubt or dispute):

indisputable

WordNet sense 9 (established beyond doubt or question; definitely known):

certain

WordNet sense 10 (exercising caution or showing care or attention):

careful

WordNet sense 11 (definitely or positively (`sure' is sometimes used informally for `surely')):

certainly, surely, for sure, sure as shooting, sure enough, for certain