certain

Having or feeling no doubt or uncertainty; confident and assured.

“felt certain of success”

“was sure (or certain) she had seen it”

Certain to occur; destined or inevitable.

“he was certain to fail”

“his fate is certain”

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”

“to a certain degree”

Established beyond doubt or question; definitely known.

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

“it is certain that they were on the bus”