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Definitions

sure

[shoor, shur] / ʃʊər, ʃɜr /
ADJECTIVE
certain, definite
Synonyms
STRONGEST
assured clear confident convinced positive
WEAK
abiding changeless constant convincing decided doubtless enduring firm fixed for a fact free from doubt genuine incontestable incontrovertible indisputable indubitable never-failing persuaded real satisfied set steadfast steady telling unchangeable unchanging uncompromising undeniable unequivocal unfailing unfaltering unqualified unquestionable unquestioning unshakable unshaken unvarying unwavering valid
Antonyms
STRONGEST
doubtful uncertain unsure
WEAK
doubted dubious humbled indefinite swerving unconfident unself-confident unsteady variable wavering wobbly
ADJECTIVE
physically stable
Synonyms
STRONGEST
fast safe strong
WEAK
firm fixed secure solid staunch steady
Antonyms
WEAK
doubted doubtful dubious humbled indefinite swerving uncertain unconfident unself-confident unsteady unsure variable wavering wobbly
ADJECTIVE
inevitable
Synonyms
STRONGEST
assured certain
WEAK
bound guaranteed indisputable ineluctable inerrant inescapable infallible irrevocable surefire unavoidable unerring unfailing
Antonyms
STRONGEST
doubtful doubting hesitant uncertain
WEAK
doubted dubious humbled indefinite swerving unconfident unself-confident unsteady unsure variable wavering wobbly
ADJECTIVE
self-confident
Synonyms
STRONGEST
assured certain confident decisive positive
WEAK
arrogant composed decided self-assured self-possessed
Antonyms
STRONGEST
doubtful doubting hesitant indefinite uncertain unsure
WEAK
doubted dubious humbled swerving unconfident unself-confident unsteady variable wavering wobbly

Usage

What are other ways to say sure? Sure, the simplest and most general of a group of adjectives indicating full belief and trust that something is true, expresses the mere absence of doubt. Certain suggests that there are definite reasons that have freed one from doubt. Confident emphasizes the strength of the belief or the certainty of expectation felt. Positive implies emphatic certainty, which may even become overconfidence or dogmatism. 

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

To make sure the spacecraft was precisely lined up for the maneuver, the operations team carried out a trajectory correction maneuver on Feb. 23.

From Science Daily • May 11, 2026

Newly-created exam body Qualifications Scotland said all papers were checked to make sure they are "clear, fair and suitable".

From BBC • May 11, 2026

I’m not sure how to handle it at work.

From MarketWatch • May 11, 2026

I’m not sure if I’ll be seeing “Full Phil” in a ballgown or blue jeans and I don’t really care.

From Los Angeles Times • May 11, 2026

At the beginning of the summer, I was pretty sure we both were.

From "Legendary Frybread Drive-In" by Cynthia Leitich Smith