Definition of "be"
To exist; to have real existence.
With there as dummy subject: to exist.
To occupy a place.
To occur, to take place.
Elliptical form of "be here", "go to and return from" or similar.
Used to indicate that the subject and object are the same.
Used to indicate that the values on either side of an equation are the same.
Used to indicate that the subject plays the role of the predicate nominal.
Used to connect a noun to an adjective that describes it.
Used to indicate that the subject has the qualities described by a noun or noun phrase.
Used to form the passive voice.
Used to form the continuous forms of various tenses.
Used to form the perfect aspect with certain intransitive verbs, most of which indicate motion. Often still used for "to go".
Used to form future tenses, especially the future periphrastic.
Used to link a subject to a count or measurement.
Used to indicate passage of time since the occurrence of an event.
Used to indicate weather, air quality, or the like.