sure 
(shr, shûr)
(shr, shûr)adj. sur·er, sur·est
1. Confident, as of something awaited or expected: I am sure we will win the game.
2. Impossible to doubt or dispute; certain: We have sure proof of his innocence.
3.
a. Bound to come about or happen; inevitable: a sure victory for the team.
b. Having one's course directed; destined or bound: She is sure to succeed.
4.
a. Certain not to miss, slip, or err; steady: a sure grip on the suitcase.
b. Not hesitating or wavering; firm: sure convictions.
5.
a. Worthy of being trusted or depended on; reliable: a sure friend.
b. Free from or marked by freedom from doubt: She is sure of her friends.
6. Careful to do something: Be sure to turn off the stove.
7. Obsolete Free from harm or danger; safe.
adv.
Informal
Idioms: Informal
Surely; certainly.
for sure Informal
Certainly; unquestionably: We'll win for sure.
make sure
To establish something without doubt; make certain: Make sure he writes it down.
sure enough
As one might have expected; certainly.
to be sure
Indeed; certainly.
[Middle English, from Old French, safe, from Latin sēcūrus; see SECURE.]
sureness n.
Synonyms: sure, certain, confident, positive
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). "We went that early because we were certain it was the only way we would ever get a seat" (Ann Patchett).
Confident suggests assurance founded on faith or reliance in oneself or in others: "It goes without saying that a smiling, confident person will do better in an interview than a surly one" (Barbara Ehrenreich).
Positive suggests full, emphatic certainty: "We were young, and I was positive nothing really terrible could happen to us" (Nora Roberts). See Also Synonyms at certain.
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). "We went that early because we were certain it was the only way we would ever get a seat" (Ann Patchett).
Confident suggests assurance founded on faith or reliance in oneself or in others: "It goes without saying that a smiling, confident person will do better in an interview than a surly one" (Barbara Ehrenreich).
Positive suggests full, emphatic certainty: "We were young, and I was positive nothing really terrible could happen to us" (Nora Roberts). See Also Synonyms at certain.