sure
Physically secure and certain, non-failing, reliable.
Certain in one's knowledge or belief.
(followed by a ''to'' infinitive) Certain to act or be a specified way.
(obsolete) Free from danger; safe; secure.
(obsolete) Betrothed; engaged to marry.
(modal adverb) Without doubt, certainly.
(archaic) Without fail, surely.
(in response to a request for help or a favour) Yes; of course.
(in response to other questions) Yes; I guess; you could say that; {{non-gloss|a weak or noncommittal positive response}}.
You're welcome; {{n-g|polite response to being thanked}}.