Tra từ sure - Từ điển Oxford Advanced Learner 8th

sure [sure surer surest] adjective, adverb BrE [ʃʊə(r)] BrE [ʃɔː(r)] NAmE [ʃʊr]
adjective (surer, sur·est) You can also use more sure and most sure, especially in sense 1.
1. not before noun confident that you know sth or that you are right
Syn: ↑certain
• ‘Is that John over there?’ ‘ I'm not sure ’.
• You don't sound very sure.
•~ (that)… I'm pretty sure (that) he'll agree.
•Are you sure you don't mind?
•I'm sure he's still alive.
•~ of sth I hope you are sure of your facts.
•~ about sth Are you sure about that?
•~ how, whether, etc… Ask me if you're not sure how to do it.
•I'm not sure whether I should tell you this.
Opp: ↑unsure
2. not before noun certain that you will receive sth or that sth will happen
•~ of sth You're always sure of a warm welcome there.
• We could not be sure of financial support.
•~ of doing sth England must win this game to be sure of qualifying for the World Cup.
3. ~ to do sth certain to do sth or to happen
• The exhibition is sure to be popular.
• It's sure to rain.
•You're sure to get lost if you don't keep to the path.
4. usually before noun that can be trusted or relied on
• It's a sure sign of economic recovery.
• There's only one sure way to do it.
•He is a sure bet for the presidential nominations (= certain to succeed).
5. usually before noun steady and confident
•We admired her sure touch at the keyboard.

Word Origin:
Middle English: from Old French sur, from Latin securus ‘free from care’.

Synonyms:
certain
bound • sure • definite • guaranteed
These are all words describing sth that will definitely happen or is definitely true.
certain • that you can rely on to happen or be true: ▪ It's certain that they will agree. ◇ ▪ They are certain to agree.
bound • [not before noun] certain to happen, or to do or be sth. Bound is only used in the phrase bound to do/be, etc.: ▪ There are bound to be changes when the new system is introduced. ◇ ▪ You've done so much work— you're bound to pass the exam.
sure • certain to happen or be true; that can be trusted on relied on: ▪ She's sure to be picked for the team. ◇ ▪ It's sure to rain.
definite • (rather informal) certain to happen; that is not going to change: ▪ Is it definite that he's leaving?
guaranteed • certain to have a particular result: ▪ That kind of behaviour is guaranteed to make him angry.
certain/sure of sth
certain/bound/sure/guaranteed to do sth
certain/definite that…
I couldn't say for certain/sure/definite.

Synonyms:
sure
confident • convinced • certain • positive • clear
These words all describe sb who knows without doubt that sth is true or will happen.
sure • [not before noun] without any doubt that you are right, that sth is true, that you will get sth or that sth will happen: ▪ ‘Is that John over there?’ ‘I'm not sure.’ ◇ ▪ Are you sure about that? ◇ ▪ England must win this game to be sure of qualifying.
Sure is often used in negative statements and questions, because there is some doubt or anxiety over the matter. If there is no doubt, people often say quite sure: ▪ I'm quite sure (that) I left my bag here ▪ (= I have no doubt about it) ▪.
confident • completely sure that sth will happen in the way that you want or expect: ▪ I'm quite confident that you'll get the job. ◇ ▪ The team feels confident of winning.
Confident is a stronger and more definite word than sure and is more often used in positive statements, when you feel no anxiety.
convinced • [not before noun] completely sure that sth is true or right, especially because the evidence seems to prove it or sb else has persuaded you to believe it: ▪ I'm convinced that she's innocent.
certain • [not usually before noun] sure that you are right or that sth is true: ▪ Are you absolutely certain about this?
sure or certain?
Like sure, certain is often used in negative statements and questions. It is slightly more formal than sure; sure is more frequent, especially in spoken English.
positive • [not before noun] (rather informal) completely sure that sth is true: ▪ She was positive that he'd been there. ◇ ▪ ‘Are you sure?’ ‘Positive.’
clear • (often used in negative statements and questions) having no doubt or confusion about sth: ▪ My memory isn't really clear on that point.
sure/confident/convinced/certain/positive/clear about sth
sure/confident/convinced/certain of sth
sure/confident/convinced/certain/positive/clear that…
sure/certain/clear who/what/how, etc.
to feel sure/confident/convinced/certain/positive
quite/absolutely/completely/fairly/pretty sure/confident/convinced/certain/positive/clear
not altogether sure/confident/convinced/certain/clear

Example Bank:
•Make sure no one finds out about this.
•Potts was confident of taking the American title, but less sure about the world championship.
•To make doubly sure they would not be disturbed she turned the key in the lock.
•What makes you so sure she'll come back to you?
•You don't seem very sure to me.
•You'd better be completely sure of your facts.
•‘Is that John over there?’ ‘I'm not sure.’
•Ask me if you're not sure how to do it.
•England must win this game to be sure of qualifying.
•He's a sure bet for the presidential nomination.
•I told my friends that our winning was a sure thing.
•I'm not sure whether I should tell you this.
•I'm pretty sure (that) he'll agree.
•I'm quite sure (that) I left my bag here.
•It's a sure sign of economic recovery.
•It's sure to rain.
•She's sure to be picked for the team.
•There's only one sure way of knowing.
•You're always sure of a warm welcome here.
•You're sure to get lost if you don't keep to the path.
Idioms: ↑be sure ▪ ↑for sure ▪ ↑make sure ▪ ↑sure as eggs is eggs ▪ ↑sure enough ▪ ↑sure of yourself ▪ ↑sure thing ▪ ↑sure to do something

adverb (informal, especially NAmE)
1. used to say ‘yes’ to sb
• ‘Will you open the wine?’ ‘Sure, where is it?’
• Did it hurt? Sure it hurt.
•Sure, no problem.
2. used to emphasize sth that you are saying
•Boy, it sure is hot.
•‘Amazing view’. ‘Sure is.’
•That song sure as hell sounds familiar.
•He sure looked unhappy.
3. used to reply to sb who has just thanked you for sth
•‘Thanks for the ride.’ ‘Sure— anytime.’

Word Origin:
Middle English: from Old French sur, from Latin securus ‘free from care’.