Real Dictionary

dream
You can use dream to describe something that you think is ideal or perfect, especially if it is something that you thought you would never be able to have or experience.
countable noun: A dream is an imaginary series of events that you experience in your mind while you are asleep.
countable noun: You can refer to a situation or event as a dream if you often think about it because you would like it to happen.
singular noun: If you describe something as a particular person's dream, you think that it would be ideal for that person and that he or she would like it very much.
singular noun: If you say that something is a dream, you mean that it is wonderful.
verb: If you often think about something that you would very much like to happen or have, you can say that you dream of it.
verb: When you dream, you experience imaginary events in your mind while you are asleep.

dream in American English
a sequence of sensations, images, thoughts, etc. passing through a sleeping person's mind
to have a dream or dreams
intransitive verb: to have a dream
noun: a succession of images, thoughts, or emotions passing through the mind during sleep
transitive verb: to see or imagine in sleep or in a vision

dream in British English
noun: mental activity, usually in the form of an imagined series of events, occurring during certain phases of sleep