certain
word
Definition
Used to show that you are sure about something, or to refer to a particular but unspecified person or thing. It can mean 'sure' or 'some' depending on the context.
Usage & Nuances
'Certain' is formal or neutral. Used before nouns ('a certain person'), or for expressing confidence ('I'm certain'). Not usually used for percentages ('100% certain' is correct, but not 'certain percent'). Can be confused with 'sure'; 'certain' is stronger or more formal. In questions, 'Are you certain?' is more formal than 'Are you sure?'.
Example Sentences
I'm certain that he will come.
basic
You need certain skills for this job.
basic
He is not certain about the answer.
basic
There are certain rules you have to follow here.
natural
If you want to be certain, you should double-check the facts.
natural
For certain people, coffee is a must in the morning.
natural