Meaning of “dream” - Learner’s Dictionary

dream

noun uk us /driːm/
SLEEP [ C ]

A2 a series of events and images that happen in your mind while you are sleeping:

a bad dream
I had a very strange dream last night.
HOPE [ C ]

B1 something that you want to happen although it is not very likely:

It was his dream to become an actor.
be in a dream UK

B2 to not notice things that are around you because you are thinking about something else

(Definition of “dream noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)