The Collaborative International Dictionary of English v.0.48:

Subway \Sub"way`\, n.
   1. An underground way or gallery; especially, a passage under
      a street, in which water mains, gas mains, telegraph
      wires, etc., are conducted.
      [1913 Webster]

   2. An underground railroad, usually having trains powered by
      electricity provided by an electric line running through
      the underground tunnel. It is usually confined to the
      center portion of cities; -- called also tube, and in
      Britain, underground. In certain other countries (as in
      France or Russia) it is called the metro.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Tube \Tube\, n. [L. tubus; akin to tuba a trumpet: cf F. tube.]
   1. A hollow cylinder, of any material, used for the
      conveyance of fluids, and for various other purposes; a
      pipe.
      [1913 Webster]

   2. A telescope. "Glazed optic tube." --Milton.
      [1913 Webster]

   3. A vessel in animal bodies or plants, which conveys a fluid
      or other substance.
      [1913 Webster]

   4. (Bot.) The narrow, hollow part of a gamopetalous corolla.
      [1913 Webster]

   5. (Gun.) A priming tube, or friction primer. See under
      Priming, and Friction.
      [1913 Webster]

   6. (Steam Boilers) A small pipe forming part of the boiler,
      containing water and surrounded by flame or hot gases, or
      else surrounded by water and forming a flue for the gases
      to pass through.
      [1913 Webster]

   7. (Zool.)
      (a) A more or less cylindrical, and often spiral, case
          secreted or constructed by many annelids, crustaceans,
          insects, and other animals, for protection or
          concealment. See Illust. of Tubeworm.
      (b) One of the siphons of a bivalve mollusk.
          [1913 Webster]

   8. (Elec. Railways) A tunnel for a tube railway; also
      (Colloq.), a tube railway; a subway. [Chiefly Eng.]

   Note: In the New York area, the subways running under the
         Hudson River are sometimes referred to as the tube.
         [Webster 1913 Suppl. +PJC]

   Capillary tube, a tube of very fine bore. See Capillary.


   Fire tube (Steam Boilers), a tube which forms a flue.

   Tube coral. (Zool.) Same as Tubipore.

   Tube foot (Zool.), one of the ambulacral suckers of an
      echinoderm.

   Tube plate, or Tube sheet (Steam Boilers), a flue plate.
      See under Flue.

   Tube pouch (Mil.), a pouch containing priming tubes.

   Tube spinner (Zool.), any one of various species of spiders
      that construct tubelike webs. They belong to Tegenaria,
      Agelena, and allied genera.

   Water tube (Steam Boilers), a tube containing water and
      surrounded by flame or hot gases.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tube \Tube\, v. t. [imp. & p. p. Tubed; p. pr. & vb. n.
   Tubing.]
   To furnish with a tube; as, to tube a well.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tube
    n 1: conduit consisting of a long hollow object (usually
         cylindrical) used to hold and conduct objects or liquids or
         gases [syn: tube, tubing]
    2: electronic device consisting of a system of electrodes
       arranged in an evacuated glass or metal envelope [syn:
       tube, vacuum tube, thermionic vacuum tube, thermionic
       tube, electron tube, thermionic valve]
    3: a hollow cylindrical shape [syn: pipe, tube]
    4: (anatomy) any hollow cylindrical body structure [syn: tube,
       tube-shaped structure]
    5: an electric railway operating below the surface of the ground
       (usually in a city); "in Paris the subway system is called
       the `metro' and in London it is called the `tube' or the
       `underground'" [syn: metro, tube, underground, subway
       system, subway]
    v 1: provide with a tube or insert a tube into
    2: convey in a tube; "inside Paris, they used to tube mail"
    3: ride or float on an inflated tube; "We tubed down the river
       on a hot summer day"
    4: place or enclose in a tube

Moby Thesaurus II by Grady Ward, 1.0:

194 Moby Thesaurus words for "tube":
   Amtrak, L, Photronic cell, adjutage, amplifier, anode, attenuator,
   audio-frequency tube, baggage train, ballast regulator,
   ballast tube, barrel, base, beam-switching tube, bole, branch,
   cable railroad, cable railway, cask, catheter, cathode,
   cathode-ray tube, channel, choo-choo, cog railroad, cog railway,
   color kinescope, column, convertor, current regulator, cylinder,
   cylindroid, damper, detector, direct-viewing tube, discharge tube,
   discriminator, dissector tube, doubler, drainpipe, drum,
   efflux tube, el, electric, electric railway, electric train,
   electrode, electron-image tube, elevated, elevated railway,
   embankment, express, express train, feeder, feeder line, filament,
   fire hose, flier, flue pipe, flume, focus tube, freight,
   freight train, freighter, funicular, funnel, garden hose,
   gas phototube, gas pipe, generator, goods train,
   gravity-operated railway, grid, horse railway, hose, hosepipe,
   iconoscope, image dissector, image iconoscope, interurban,
   inverter, junction, kinescope, light railroad, lightning express,
   limited, limiter, line, local, local-oscillator tube, main line,
   metro, milk train, mixer tube, modulator, monorail, monoscope,
   multiplier, multiplier phototube, multipurpose tube, multivibrator,
   nipple, organ pipe, oscillator, output tube, parliamentary,
   parliamentary train, passenger train, phase inverter, photocathode,
   photoconductor cell, photomultiplier tube, phototube,
   photovoltaic cell, picture tube, pillar, pipe, pipeline, pipette,
   piping, plate, power tube, pulse generator, put through channels,
   rack railway, rack-and-pinion railroad, rack-and-pinion railway,
   radio tube, radio-frequency tube, rail, rail line, railroad,
   railroad train, railway, rattler, receiving tube, rectifier tube,
   reed, reed pipe, regulator, repeater, roadbed, roadway, roll,
   roller, rolling stock, rouleau, shuttle, shuttle train, siamese,
   siamese connection, sidetrack, siding, siphon, snorkel,
   soft phototube, soil pipe, special, standpipe, steam pipe, stem,
   straw, streamliner, street railway, streetcar line, subway,
   switchback, tap, terminal, terminus, track, train, tram, tramline,
   transducer, trestle, trigatron, trigger tube, trolley line, trunk,
   trunk line, tubing, tubulation, tubule, tubulet, tubulure, turnout,
   underground, vacuum phototube, vacuum tube, valve, waste pipe,
   water pipe, way train



The Jargon File (version 4.4.7, 29 Dec 2003):

tube


    1. n. A CRT terminal. Never used in the mainstream sense of TV; real
    hackers don't watch TV, except for Looney Toons, Rocky & Bullwinkle, Trek
    Classic, the Simpsons, Babylon 5, and the occasional cheesy old
    swashbuckler movie.

    2. [IBM] To send a copy of something to someone else's terminal. ?Tube me
    that note??


The Free On-line Dictionary of Computing (30 December 2018):

tube

   1.  A CRT terminal.  Never used in the mainstream
   sense of TV; real hackers don't watch TV, except for Loony
   Toons, Rocky & Bullwinkle, Trek Classic, the Simpsons, and the
   occasional cheesy old swashbuckler movie.

   2.  electron tube.

   3.  (IBM) To send a copy of something to someone
   else's terminal.  "Tube me that note."

   [Jargon File]

   (1996-02-05)