reliable, trusted, trusty, trustworthy, dependable, confident, convinced, sure enough, certain, certainly, more...

uncertain, doubtful, unsure, hesitant, indecisive

certain, confident, convinced, positive, absolutely, more...

dead, damned, certain, real, old, darn, full, little, bloody, goddamned, double

let's do it,   "no problem",   "you betcha!",   more certain,   yeah right,   certain term,   certain to,   certain something,   was certain,   pretty confident,   it's definite,   most certain