certain
//ˈsɜːtn//
Adjective
1
Completely sure or confident about something; having no doubt.
I am certain that I locked the door before leaving.
2
Known to be true or definite; established as a fact.
It is certain that the sun will rise tomorrow.
3
Reliable or dependable; sure to happen or occur.
Victory is certain if we follow the plan.
Determiner
1
Used to refer to a specific but unidentified person, thing, or amount.
There are certain things I need to tell you.
2
Some but not very much; a moderate amount of.
The plan has a certain amount of risk.
Pronoun
1
Some people or things; particular but unspecified ones.
Certain of the students stayed after class to ask questions.