free from doubt as to the reliability, character, action, etc., of something

to be sure of one's data.

confident, as of something expected

sure of success.

convinced, fully persuaded, or positive

to be sure of a person's guilt.

assured or certain beyond question

a sure victory.

worthy of confidence; reliable; stable

a sure messenger.

unfailing; never disappointing expectations

a sure cure.

unerring; never missing, slipping, etc.

a sure aim.

admitting of no doubt or question

sure proof.

destined; bound inevitably; certain

sure death.

Obsolete . secure; safe.

be sure, to take care (to be or do as specified); be certain

Be sure to close the windows.

Informal . certainly; surely

It sure is cold out. Sure, I'll come.

for sure

as a certainty; surely

It's going to be a good day, for sure.

make sure

to be or become absolutely certain

I'm calling to make sure that you remember to come.

sure enough

Informal . as might have been supposed; actually; certainly

Sure enough, the picnic was rained out.

to be sure

without doubt; surely; certainly.

admittedly

She sings well, to be sure, but she can't act.

adjective

doubtful , dubious , indefinite , uncertain , unsure , variable , wavering , swerving , unsteady , wobbly , doubted , humbled , unconfident , unself-confident

adjective

abiding , assured , changeless , clear , confident , constant , convinced , convincing , decided , doubtless , enduring , firm , fixed , for a fact , free from doubt , genuine , incontestable , incontrovertible , indisputable , indubitable , never-failing , persuaded , positive , real , satisfied , set , steadfast , steady , telling , unchangeable , unchanging , uncompromising , undeniable , unequivocal , unfailing , unfaltering , unqualified , unquestionable , unquestioning , unshakable , unshaken , unvarying , unwavering , valid , fast , safe , secure , solid , staunch , strong , bound , certain , guaranteed , ineluctable , inerrant , inescapable , infallible , irrevocable , surefire , unavoidable , unerring , arrogant , composed , decisive , self-assured , self-possessed , hard , inarguable , irrefutable , unassailable , undisputable , inevitable , stable , sturdy , substantial , undoubting , authentic , definite , dependable , inerrable , reliable , rue , sanguine , trustworthy , undoubted