marked by or given to feelings of confident certainty
Are you sure you're right?
(+ of) confident that something is true, will happen, etc
certain; bound
She is sure to win
not in any doubt; true and reliable
reliable
a sure sign
for sure
as a certainty
to be sure
it must be acknowledged; admittedly
sureness noun
[Middle English via French sur from Latin securus: see secure1]