Without a Doubt

You use the expression ‘Without A Doubt’ to indicate that there is no uncertainty
about something.

Example of use: “Does she love him?” Answer: “Without a doubt!”

Interesting fact

No one is certain when the expression ‘without a doubt’ originated, but the English word “doubt” originated in the 13th century as a reference to the 11th century Old French “doter” which in turn was taken from the latin “dubitare.” It is likely that as long as people have had doubt or wavering opinions, there has been some form of negating expression such as the “without a doubt” we use today.