1. To come or go into: The train entered the tunnel.

2. To penetrate; pierce: The bullet entered the victim's skull.

3. To introduce; insert: She entered the probe into the patient's artery.

4. a. To become a participant, member, or part of; join: too old to enter the army; entered the discussion at a crucial moment. b. To gain admission to (a school, for example).

5. To cause to become a participant, member, or part of; enroll: entered the children in private school; entered dahlias in a flower show.

6. To embark on; begin: With Sputnik, the Soviet Union entered the space age.

7. To make a beginning in; take up: entered medicine.

8. To write or put in: We entered our names in the guest book; enters the data into the computer.

9. To place formally on record; submit: enter a plea of innocence; enter a complaint.

10. To go to or occupy in order to claim possession of (land).

11. To report (a ship or cargo) to customs.

1. To come or go in; make an entry: As the President entered, the band played "Hail to the Chief."

2. To effect penetration.

3. To become a member or participant.

1. To participate in; take an active role or interest in: enter into politics; enter into negotiations.

2. To become party to (a contract): The nations entered into a new agreement.

3. To become a component of; form a part of: Financial matters entered into the discussion.

4. To consider; investigate: The report entered into the effect of high interest rates on the market.

1. To set out on; begin: We enter on a new era in our history. They entered upon the most dangerous part of the journey.

2. To begin considering; take up: After discussing the budget deficit, they entered on the problem of raising taxes.

3. To take possession of: She entered upon the estate of her uncle.