certain

having or feeling no doubt or uncertainty; confident and assured

“felt certain of success”

certain to occur; destined or inevitable

“he was certain to fail”

exercising or taking care great enough to bring assurance

“be certain to disconnect the iron when you are through”

reliable in operation or effect

“a quick and certain remedy”

established irrevocably

definite but not specified or identified

“set aside a certain sum each week”

established beyond doubt or question; definitely known

“what is certain is that every effect must have a cause”