believe
be·lieve
 /bəˈliːv/  verb  , not used in progressive tenses, -lieves, -lieved, -liev·ing
  1 [  + obj  ]
  1 a : to accept or regard (something) as true
   The scientists believed the reports.
   Many people seem to believe that theory, but I find it hard/difficult to believe.
   You shouldn't believe everything you read.
   I knew that he was a liar and so I didn't believe a word he said. [=I didn't believe anything he said]
   I did not want to believe (that) it could happen.
   He says he'll help us, but I don't believe what he says.
   They were tricked into believing that he was a doctor.
  — opposite disbelieve
  1 b : to accept the truth of what is said by (someone)
   He says he'll help us, but I don't believe him.
  — opposite disbelieve
  2 [  + obj  ] : to have (a specified opinion) : think
   I'm beginning to believe (that) this war will never end.
   I used to believe (that) I was the only one who felt that way but now I know (that) there are others like me.
   He clearly/firmly/honestly believes (that) it is possible. = He clearly/firmly/honestly believes it (to be) possible.
   He had reason to believe that they would accept his offer. = He had reason for believing that they would accept his offer.
   She was widely believed to be guilty. [=many people believed that she was guilty]
   We were led to believe it was true. [=we heard, saw, or read something that made us think it was true]
   “Has he accepted the job?” “I believe so.” = “So I believe.”
   “Has he accepted the job?” “I believe not.” = “I don't believe so.”
  3 [  no obj  ] : to regard the existence of God as a fact : to have religious beliefs
   She went to church because her family expected it, but she didn't really believe.
  4 [  no obj  ] : to have trust in the ability, worth, etc., of someone or something
   The team hasn't won a championship in many years, but their fans still believe. [=their fans still believe in them; their fans still believe that they will win]
  5 informal
  — used for emphasis in phrases that express certainty, surprise, annoyance, etc.
   “Do you think they can win?” “You/You'd better believe it!” [=yes, I definitely think so]
   Believe me, he can really play the game. = Believe you me, he can really play the game.
   I can't believe how ugly that dress is. [=what an ugly dress]
   You broke the window? I can't believe you guys! [=I'm annoyed and shocked by what you did] How could you do such a thing?
   I can't believe [=I am amazed/surprised] that that terrible restaurant is still in business.
   That terrible restaurant is still in business, if you can believe it/that.
   Can/Would you believe it?! That terrible restaurant is still in business.
   You won't believe what I just heard! [=you will be very surprised by what I just heard]
   You wouldn't believe how long it took us to get here. [=it took us a surprisingly long/short time to get here]
   I don't believe it! I swept the floor 10 minutes ago, and it's already dirty again!
   I could not believe my good fortune/luck.
   It's hard to believe that he's gone.
   His latest movie, believe it or not, is a romantic comedy about a group of lawyers. [=it is surprising but true that his latest movie is a romantic comedy about a group of lawyers]
   “I hear that their marriage is in trouble.” “Don't you believe it! [=that is completely untrue] They're the happiest couple I know!”
   “He says he's going to become a doctor.” “If you believe that, you'll believe anything!” [=it would be very foolish to believe that he is going to become a doctor]
   “He says he's going to become a doctor.” “I'll believe that when I see it!”
  believe in [  phrasal verb  ]
   1 believe in (something)
   1 a : to have faith or confidence in the existence of (something)
    Do you believe in ghosts?
   1 b : to have trust in the goodness or value of (something)
    She believes in (the value of) regular exercise.
    They believed in liberty for all.
    I believe in working hard to achieve success.
    She doesn't believe in using pesticides. [=she doesn't believe that it's right to use pesticides; she believes that pesticides do more harm than good]
   2 believe in (someone) : to have trust in the goodness or ability of (someone)
    Despite his problems, his parents still believe in him.
    She believes in herself and in her abilities.
  can't believe your eyes/ears
   ◇ If you can't believe your eyes/ears or can hardly/scarcely believe your eyes/ears, you are very surprised at or upset by what you are seeing or hearing.
    I could hardly believe my eyes when I saw what he was wearing.
   
  make believe
   : to act as though something that is not true or real is true or real : pretend
    When we were children we used to make believe (that) we were soldiers fighting in a war.
    He isn't really angry, he's just making believe (that he is).
    They want to make believe that everything is all right.
    — see also make-believe
  seeing is believing
   ◇ The expression seeing is believing means that when you actually see something, you have to believe that it exists or is true.
    I didn't think it could happen, but seeing is believing. [=I saw it happen, so now I believe it's possible]
   
  be·liev·able /bəˈliːvəbəl/  adj   [more ~; most ~]
   The novel's ending is not very believable.
   His excuse was barely/scarcely believable.
  be·liev·ably /bəˈliːvəbli/  adv  
   The characters are all believably portrayed.
  be·liev·er  noun  ,  pl   -ers [  count  ]
   a believer in religion
   devout believers
   She's a firm/great/strong believer in adult education. [=she firmly/strongly believes in the value of adult education; she thinks adult education is very useful and important]
   I was doubtful that he could run his own company, but he's made a believer out of me. = He's made me a believer. [=he's convinced me that he can run his own company]