sure

The definition of sure is someone or something which is certain, trustworthy or always effective.

(adjective)

An example of sure is someone who's positive they're getting a job for which they interviewed.

See sure in Webster's New World College Dictionary

adjective surer, surest

Obsolete secure or safe
that will not fail; always effective: a sure method
that can be relied upon; trustworthy: a sure friend
that cannot be doubted, questioned, or disputed; absolutely true; certain
having or showing no doubt; positive; confident: to be sure of one's facts
that can be counted on to be or happen: a sure defeat
bound or destined to do, experience, or be something specified: sure to be elected
never missing; unerring: a sure aim

Origin: OFr seur < L securus: see secure

surely; inevitably
certainly; indeed: an intensive, often used as an affirmative answer to questions

Related Forms:

See sure in American Heritage Dictionary 4

adjective sur·er, sur·est

Impossible to doubt or dispute; certain.
Not hesitating or wavering; firm: sure convictions.
Confident, as of something awaited or expected: sure of ultimate victory.
a. Bound to come about or happen; inevitable: sure defeat.
b. Having one's course directed; destined or bound: sure to succeed.
Certain not to miss or err; steady: a sure hand on the throttle.
a. Worthy of being trusted or depended on; reliable.
b. Free from or marked by freedom from doubt: sure of her friends.
Careful to do something: asked me to be sure to turn off the stove.
Obsolete Free from harm or danger; safe.