What does CERTAIN mean?

adjective

1. definite but not specified or identified“set aside a certain sum each week”
2. having or feeling no doubt or uncertainty; confident and assured“felt certain of success”
3. established beyond doubt or question; definitely known“what is certain is that every effect must have a cause”
4. certain to occur; destined or inevitable“he was certain to fail”
5. established irrevocably“his fate is sealed”
6. reliable in operation or effect“a quick and certain remedy”
7. exercising or taking care great enough to bring assurance“be certain to disconnect the iron when you are through”