Synonyms and antonyms of To be certain in British Thesaurus

be clear that (adjective)

to feel confident and determined about a belief or decision

know (verb)

to feel certain about something

believe in ()

to feel confident that a person or organization is good or reliable

know your own mind ()

to be certain about what you like and what you want

swear to ()

to be completely certain of something

depend on ()

if you can depend on someone to do something, you are sure that they will do it

feel/know something in your bones ()

to feel certain about something, although you cannot explain or prove it

bet the farm ()

to be certain that something will happen or bring you success, especially when this makes you spend all your money on it