to come or go in

Knock before you enter.

to be admitted into a school, competition, etc.

Some contestants enter as late as a day before the race.

to make a beginning (often fol. by on or upon )

We have entered upon a new phase in history.

Theater . to come upon the stage (used in stage directions as the 3rd person imperative sing. or pl.)

Enter Othello, and Iago at a distance.

to come or go into

He just entered the building. The thought never entered my mind.

to penetrate or pierce

The bullet entered the flesh.

to put in or insert.

to become a member of; join

to enter a club.

to cause to be admitted, as into a school, competition, etc.

to enter a horse in a race.

to make a beginning of or in, or begin upon; engage or become involved in

He entered the medical profession.

to share in; have an intuitive understanding of

In order to appreciate the novel, one must be able to enter the spirit of the work.

to make a record of; record or register

to enter a new word in a dictionary.

Law .

to make a formal record of (a fact).

to occupy or to take possession of (lands); make an entrance, entry, ingress in, under claim of a right to possession.

to file an application for (public lands).

Computers . to put (a document, program, data, etc.) into a computer system

Enter your new document into the word-processing system.

to put forward, submit, or register formally

to enter an objection to a proposed action; to enter a bid for a contract.

to report (a ship, cargo, etc.) at the custom house. ?

enter into,

to participate in; engage in.

to investigate; consider

We will enter into the question of inherited characteristics at a future time.

to sympathize with; share in.

to form a constituent part or ingredient of

There is another factor that enters into the situation.

to go into a particular state

to enter into a state of suspended animation.