Sure and surely are both used as simple intensives. Sure is informal and typically used when the speaker or writer expects to be agreed with. She sure knew how to make me laugh. That sure was fun. Surely can occur in formal contexts and is used whether or not agreement is expected.
SURE meaning: 1. certain; without any doubt: 2. certain or certainly: 3. to be very or too confident: . Learn more.
Sure is used to emphasize that something such as a sign or ability is reliable or accurate.
These adjectives mean feeling or showing no doubt. Sure and certain are frequently used interchangeably; sure, however, is the more subjective term, whereas certain may imply belief based on experience or evidence: "Never teach a child anything of which you are not yourself sure" (John Ruskin).
Being sure has to do with being certain, convinced, trustworthy, or dependable. You can trust a sure thing.
Sure, certain, confident, positive indicate full belief and trust that something is true. Sure, certain, and positive are often used interchangeably. Sure, the simplest and most general, expresses mere absence of doubt. Certain suggests that there are definite reasons that have freed one from doubt.
idiom (make sure) To establish something without doubt; make certain. idiom (sure enough) As one might have expected; certainly. idiom (to be sure) Indeed; certainly. from The Century Dictionary. Certainly; without doubt; doubtless; surely. Firmly; securely. Confident; undoubting; having no fear of being deceived or disappointed.
SURE definition: free from doubt as to the reliability, character, action, etc., of something. See examples of sure used in a sentence.