Definition of believe verb from the Oxford Advanced Learner's Dictionary

Oxford3000

believe

verb
bɪˈliːv
 
; bɪˈliːv
 
 
(not used in the progressive tenses)
 

feel certain

1 [transitive] to feel certain that something is true or that somebody is telling you the truthbelieve somebody I don't believe you!The man claimed to be a social worker and the old woman believed him.Believe me, she's not right for you.believe something I believed his lies for years.I find that hard to believe.Don't believe a word of it(= don't believe any part of what somebody is saying).believe (that)… People used to believe (that) the earth was flat.He refused to believe (that) his son was involved in drugs.I do believe you're right (= I think something is true, even though it is surprising).
 

think possible

2 [intransitive, transitive] to think that something is true or possible, although you are not completely certain‘Where does she come from?’ ‘Spain, I believe.’‘Does he still work there?’ ‘I believe so/not.’believe (that)… Police believe (that) the man may be armed.it is believed (that)… It is believed that the couple have left the country.believe somebody/something to be, have, etc. something The vases are believed to be worth over $20000 each.believe somebody/something + adjective Three sailors are missing, believed drowned.
 

have opinion

3 [transitive] believe (that)… to have the opinion that something is right or trueThe party believes (that) education is the most important issue facing the government.She believes that killing animals for food or fur is completely immoral.
 

be surprised/annoyed

4 [transitive] don't/can't ~ used to say that you are surprised or annoyed at somethingbelieve (that)… She couldn't believe (that) it was all happening again.I don't believe I'm doing this!believe how, what, etc… I can't believe how much better I feel.
 

religion

5 [intransitive] to have a religious faithThe god appears only to those who believe.
Idioms

believe it or not

(informal) used to introduce information that is true but that may surprise peopleBelieve it or not, he asked me to marry him!

believe (you) me

(informal) used to emphasize that you strongly believe what you are sayingYou haven't heard the last of this, believe you me!

don't you believe it!

(informal) used to tell somebody that something is definitely not true‘She wouldn't do a thing like that.’ ‘Don't you believe it!’

I don't believe it!

(informal) used to say that you are surprised or annoyed about somethingI don't believe it! What are you doing here?

if you believe that, you'll believe anything

(informal) used to say that you think somebody is stupid if they believe that something is true‘He promised not to do it again.’ ‘Sure, and if you believe that, you'll believe anything.’

make believe (that…)

to pretend that something is true
related noun make-believe

not believe your ears/eyes

(informal) to be very surprised at something you hear/seeI couldn't believe my eyes when she walked in.

seeing is believing

(saying) used to say that somebody will have to believe that something is true when they see it, although they do not think it is true now

would you believe (it)?

(informal) used to show that you are surprised and annoyed about somethingAnd, would you believe, he didn't even apologize!

you/you'd better believe it!

(informal) used to tell somebody that something is definitely true‘He's not a bad player, is he?’ ‘You'd better believe it!’
more at give somebody to believe/understand at give v.
Phrasal verbs

believe in somebody/something

to feel certain that somebody/something existsDo you believe in God?

believe in somebody

to feel that you can trust somebody and/or that they will be successfulThey need a leader they can believe in.I never thought I could make it as an actor, but my parents always believed in me.

believe in something

to think that something is good, right or acceptableDo you believe in capital punishment?believe in something doing something I don't believe in hitting children.

believe something of somebody

to think that somebody is capable of somethingAre you sure he was lying? I can't believe that of him.
Usage noteUsage note: according toReporting someone's opinionPhotography is, according to Vidal, the art form of untalented people.For Vidal, photography is the art form of untalented people.His view is that photography is not art but merely the mechanical reproduction of images.Smith takes the view that photography is both an art and a science.In Brown's view, photography should be treated as a legitimate art in its own right.James is of the opinion that a good painter can always be a good photographer if he or she so decides.Emerson believed that a photograph should only reflect what the human eye can see. Language Banks at argue, opinionUsage noteUsage note: opinionGiving your personal opinionIn my opinion, everyone should have some understanding of science.Everyone should, in my opinion, have some understanding of science.It seems to me that many people in this country have a poor understanding of science.This is, in my view, the result of a failure of the scientific community to get its message across.Another reason why so many people have such a poor understanding of science is, I believe, the lack of adequate funding for science in schools.Smith argues that science is separate from culture.My own view is that science belongs with literature, art, philosophy and religion as an integral part of our culture.In this writer's opinion, the more the public know about science, the less they will fear and distrust it. Synonyms at think Language Banks at according to, argue, impersonal, nevertheless, perhapsUsage noteUsage note: thinkbelieve feel reckon be under the impressionThese words all mean to have an idea that something is true or possible or to have a particular opinion about somebody/something.think to have an idea that something is true or possible, although you are not completely certain; to have a particular opinion about somebody/something:Do you think (that) they'll come? Well, I like it. What do you think?believe to have an idea that something is true or possible, although you are not completely certain; to have a particular opinion about somebody/something:Police believe (that) the man may be armed.think or believe?When you are expressing an idea that you have or that somebody has of what is true or possible, believe is more formal than think. It is used especially for talking about ideas that other people have; think is used more often for talking about your own ideas:Police believe… I think… When you are expressing an opinion, believe is stronger than think and is used especially for matters of principle; think is used more for practical matters or matters of personal taste.feel to have a particular opinion about something that has happened or about what you/somebody ought to do:We all felt (that) we were unlucky to lose.reckon (informal) to think that something is true or possible:I reckon (that) I'm going to get that job.be under the impression that… to have an idea that something is true:I was under the impression that the work had already been completed.to think/believe/feel/reckon/be under the impression that…It is thought/believed/reckoned that…to be thought/believed/felt/reckoned to be somethingto think/believe/feel something about somebody/somethingto sincerely/honestly/seriously/mistakenly think/believe/feelUsage noteUsage note: trustdepend on somebody/something rely on somebody/something count on somebody/something believe in somebodyThese words all mean to believe that somebody/something will do what you hope or expect of them or that what they tell you is correct or true.trust to believe that somebody is good, honest, sincere, etc. and that they will do what you expect of them or do the right thing; to believe that something is true or correct:You can trust me not to tell anyone. Don't trust what you read in the newspapers!depend on/upon somebody/something (often used with can/cannot/could/could not) to trust somebody/something to do what you expect or want, to do the right thing, or to be true or correct:He was the sort of person you could depend on. Can you depend on her version of what happened?rely on/upon somebody/something (used especially with can/cannot/could/could not and should/should not) to trust somebody/something to do what you expect or want, or to be honest, correct or good enough:Can I rely on you to keep this secret? You can't rely on any figures you get from them.trust, depend or rely on/upon somebody/something?You can trust a person but not a thing or system. You can trust somebody's judgement or advice, but not their support. You can depend on somebody's support, but not their judgement or advice. Rely on/upon somebody/something is used especially with you can/could or you should to give advice or a promise:I don't really rely on his judgement. You can't really rely on his judgement.count on somebody/something (often used with can/cannot/could/could not) to be sure that somebody will do what you need them to do, or that something will happen as you want it to happen:I'm counting on you to help me. We can't count on the good weather lasting.believe in somebody to feel that you can trust somebody and/or that they will be successful:They need a leader they can believe in.to trust/depend on/rely on/count on somebody/something to do somethingto trust/believe in somebody/somethingto trust/rely on somebody's advice/judgementto depend on/rely on/count on somebody's supportto completely trust/depend on/rely on/believe in somebody/something