The Collaborative International Dictionary of English v.0.48:

Gate \Gate\ (g[=a]t), n. [OE. [yogh]et, [yogh]eat, giat, gate,
   door, AS. geat, gat, gate, door; akin to OS., D., & Icel. gat
   opening, hole, and perh. to E. gate a way, gait, and get, v.
   Cf. Gate a way, 3d Get.]
   1. A large door or passageway in the wall of a city, of an
      inclosed field or place, or of a grand edifice, etc.;
      also, the movable structure of timber, metal, etc., by
      which the passage can be closed.
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   2. An opening for passage in any inclosing wall, fence, or
      barrier; or the suspended framework which closes or opens
      a passage. Also, figuratively, a means or way of entrance
      or of exit.
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            Knowest thou the way to Dover?
            Both stile and gate, horse way and footpath. --Shak.
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            Opening a gate for a long war.        --Knolles.
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   3. A door, valve, or other device, for stopping the passage
      of water through a dam, lock, pipe, etc.
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   4. (Script.) The places which command the entrances or
      access; hence, place of vantage; power; might.
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            The gates of hell shall not prevail against it.
                                                  --Matt. xvi.
                                                  18.
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   5. In a lock tumbler, the opening for the stump of the bolt
      to pass through or into.
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   6. (Founding)
      (a) The channel or opening through which metal is poured
          into the mold; the ingate.
      (b) The waste piece of metal cast in the opening; a sprue
          or sullage piece. [Written also geat and git.]
          [1913 Webster]

   Gate chamber, a recess in the side wall of a canal lock,
      which receives the opened gate.

   Gate channel. See Gate, 5.

   Gate hook, the hook-formed piece of a gate hinge.

   Gate money, entrance money for admission to an inclosure.


   Gate tender, one in charge of a gate, as at a railroad
      crossing.

   Gate valva, a stop valve for a pipe, having a sliding gate
      which affords a straight passageway when open.

   Gate vein (Anat.), the portal vein.

   To break gates (Eng. Univ.), to enter a college inclosure
      after the hour to which a student has been restricted.

   To stand in the gate or To stand in the gates, to occupy
      places or advantage, power, or defense.
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The Collaborative International Dictionary of English v.0.48:

Geat \Geat\ (g[=e]t), n. [See Gate a door.] (Founding)
   The channel or spout through which molten metal runs into a
   mold in casting. [Written also git, gate.]
   [1913 Webster]