The Collaborative International Dictionary of English v.0.48:

Enter- \En"ter-\ [F. entre between, fr. L. inter. See Inter-]
   A prefix signifying between, among, part.
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The Collaborative International Dictionary of English v.0.48:

Enter \En"ter\, v. t. [imp. & p. p. Entered; p. pr. & vb. n.
   Entering.] [OE. entren, enteren, F. entrer, fr. L. intrare,
   fr. intro inward, contr. fr. intero (sc. loco), fr. inter in
   between, between. See Inter-, In, and cf. Interior.]
   1. To come or go into; to pass into the interior of; to pass
      within the outer cover or shell of; to penetrate; to
      pierce; as, to enter a house, a closet, a country, a door,
      etc.; the river enters the sea.
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            That darksome cave they enter.        --Spenser.
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            I, . . . with the multitude of my redeemed,
            Shall enter heaven, long absent.      --Milton.
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   2. To unite in; to join; to be admitted to; to become a
      member of; as, to enter an association, a college, an
      army.
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   3. To engage in; to become occupied with; as, to enter the
      legal profession, the book trade, etc.
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   4. To pass within the limits of; to attain; to begin; to
      commence upon; as, to enter one's teens, a new era, a new
      dispensation.
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   5. To cause to go (into), or to be received (into); to put
      in; to insert; to cause to be admitted; as, to enter a
      knife into a piece of wood, a wedge into a log; to enter a
      boy at college, a horse for a race, etc.
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   6. To inscribe; to enroll; to record; as, to enter a name, or
      a date, in a book, or a book in a catalogue; to enter the
      particulars of a sale in an account, a manifest of a ship
      or of merchandise at the customhouse.
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   7. (Law)
      (a) To go into or upon, as lands, and take actual
          possession of them.
      (b) To place in regular form before the court, usually in
          writing; to put upon record in proper from and order;
          as, to enter a writ, appearance, rule, or judgment.
          --Burrill.
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   8. To make report of (a vessel or her cargo) at the
      customhouse; to submit a statement of (imported goods),
      with the original invoices, to the proper officer of the
      customs for estimating the duties. See Entry, 4.
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   9. To file or inscribe upon the records of the land office
      the required particulars concerning (a quantity of public
      land) in order to entitle a person to a right pf
      pre["e]mption. [U.S.] --Abbott.
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   10. To deposit for copyright the title or description of (a
       book, picture, map, etc.); as, "entered according to act
       of Congress."
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   11. To initiate; to introduce favorably. [Obs.] --Shak.
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The Collaborative International Dictionary of English v.0.48:

Enter \En"ter\, v. i.
   1. To go or come in; -- often with in used pleonastically;
      also, to begin; to take the first steps. "The year
      entering." --Evelyn.
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            No evil thing approach nor enter in.  --Milton.
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            Truth is fallen in the street, and equity can not
            enter.                                --Is. lix. 14.
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            For we which have believed do enter into rest.
                                                  --Heb. iv. 3.
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   2. To get admission; to introduce one's self; to penetrate;
      to form or constitute a part; to become a partaker or
      participant; to share; to engage; -- usually with into;
      sometimes with on or upon; as, a ball enters into the
      body; water enters into a ship; he enters into the plan;
      to enter into a quarrel; a merchant enters into
      partnership with some one; to enter upon another's land;
      the boy enters on his tenth year; to enter upon a task;
      lead enters into the composition of pewter.
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   3. To penetrate mentally; to consider attentively; -- with
      into.
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            He is particularly pleased with . . . Sallust for
            his entering into internal principles of action.
                                                  --Addison.
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WordNet (r) 3.0 (2006):

enter
    v 1: to come or go into; "the boat entered an area of shallow
         marshes" [syn: enter, come in, get into, get in,
         go into, go in, move into] [ant: exit, get out,
         go out, leave]
    2: become a participant; be involved in; "enter a race"; "enter
       an agreement"; "enter a drug treatment program"; "enter
       negotiations" [syn: enter, participate] [ant: chuck up
       the sponge, drop by the wayside, drop out, fall by the
       wayside, give up, quit, throw in, throw in the
       towel]
    3: register formally as a participant or member; "The party
       recruited many new members" [syn: enroll, inscribe,
       enter, enrol, recruit]
    4: be or play a part of or in; "Elections figure prominently in
       every government program"; "How do the elections figure in
       the current pattern of internal politics?" [syn: figure,
       enter]
    5: make a record of; set down in permanent form [syn: record,
       enter, put down]
    6: come on stage
    7: take on duties or office; "accede to the throne" [syn:
       accede, enter]
    8: put or introduce into something; "insert a picture into the
       text" [syn: insert, infix, enter, introduce]
    9: set out on (an enterprise or subject of study); "she embarked
       upon a new career" [syn: embark, enter]