Certitude means being 100% sure, without any doubt. He spoke with certitude about his ability to win the match.
Pro Tip 2/3
Not Hypothetical
Use 'certitude' when there's evidence or strong belief, not for guessing or speculation. After seeing the test results, we have certitude about the diagnosis.
Pro Tip 3/3
Formal Tone
'Certitude' is more formal, often used in written texts, speeches, or academic discussions. The scientist expressed certitude about the validity of the new theory.