from Cambridge dict.:
to think that something is true, correct or real:
Strangely, no one believed us when we told them we'd been visited by a creature from Mars.
[+ that] He believes that all children are born with equal intelligence.
[+ speech] She's arriving tomorrow, I believe.
"Is she coming alone?" "We believe not/so (= We think she is not/is)."
[+ object + to infinitive] I believe her to be the finest violinist in the world.
[+ object + adjective] All the crew are missing, believed dead
believe in sb phrasal verb
to trust someone because you think that they can do something well or that they are a good person:
[R] Gradually, since her divorce, she's beginning to believe in herself again.
believe in sth phrasal verb
1 to be certain that something exists:
Do you believe in ghosts?
2 to be confident that something is effective and right:
They don't believe in living together before marriage.
He believes in saying what he thinks.
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