Thesaurus Dictionary
Synonyms and antonyms of Certain about something in American Thesaurus
Certain about something
positive (adjective)
confident (adjective)
certain that something will happen or be successful
unquestioning (adjective)
never doubting or criticizing
flat out ()
completely and without doubt
positively (adverb)
unfaltering (adjective)
formal confident and strong because you believe your principles or actions are right