[not before noun] confident that you know something or that you are right synonym certain. 'Is that John over there?' 'I'm not sure.

sure · certain that you can rely on to happen or be true:It's certain that they will agree. · bound [not before noun] certain to happen, or to do or be something.

​used to emphasize something that you are saying. Boy, it sure is hot. 'Amazing view'. 'Sure is.' I sure hope you are right about that.

There are five meanings listed in OED's entry for the verb sure, four of which are labelled obsolete. See 'Meaning & use' for definitions, usage, and quotation ...

1used to say “yes” to someone “Will you open the wine?” “Sure, where is it?” Did it hurt? Sure it hurt. · 2used to emphasize something that you are saying Boy, ...

(informal) certain to be successful or to happen as you expect a sure-fire success. Bad behavior is a sure-fire way of getting people's attention.

SURE definition: 1. certain; without any doubt: 2. certain or certainly: 3. to be very or too confident: . Learn more.

sure-footed · ​not likely to fall when walking or climbing on rough ground. Take your English to the next level. The Oxford Learner's Thesaurus explains the ...

Certainly usually means 'without doubt' or 'definitely', and is used to show that you strongly believe something or to emphasize that something is really true.

sure-grounded, adj. meanings, etymology, pronunciation and more in the Oxford English Dictionary.