Meaning

• Physically secure and certain, non-failing, reliable.

  "This investment is a sure thing.   The bailiff had a sure grip on the prisoner's arm."

• Certain in one's knowledge or belief.

  "He was sure she was lying.   I am sure of my eventual death.   John was acting sure of himself but in truth had doubts."

• Certain to act or be a specified way.

  "Be sure to lock the door when you leave."

• Free from danger; safe; secure.

• Betrothed; engaged to marry.

Meaning

• (modal adverb) Without doubt, certainly.

  ""Did you kill that bear yourself?" ―"I sure did!""

Meaning

• Yes. (Expresses noncommittal agreement or consent.)

  ""Do you want me to put this in the garage?" "Sure, go ahead.""

• Yes; of course.

  ""Could you tell me where the washrooms are?" "Sure, they're in the corner over there.""