The Collaborative International Dictionary of English v.0.48:

Heavy \Heav"y\, a. [Compar. Heavier; superl. Heaviest.] [OE.
   hevi, AS. hefig, fr. hebban to lift, heave; akin to OHG.
   hebig, hevig, Icel. h["o]figr, h["o]fugr. See Heave.]
   1. Heaved or lifted with labor; not light; weighty;
      ponderous; as, a heavy stone; hence, sometimes, large in
      extent, quantity, or effects; as, a heavy fall of rain or
      snow; a heavy failure; heavy business transactions, etc.;
      often implying strength; as, a heavy barrier; also,
      difficult to move; as, a heavy draught.
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   2. Not easy to bear; burdensome; oppressive; hard to endure
      or accomplish; hence, grievous, afflictive; as, heavy
      yokes, expenses, undertakings, trials, news, etc.
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            The hand of the Lord was heavy upon them of Ashdod.
                                                  --1 Sam. v. 6.
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            The king himself hath a heavy reckoning to make.
                                                  --Shak.
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            Sent hither to impart the heavy news. --Wordsworth.
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            Trust him not in matter of heavy consequence.
                                                  --Shak.
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   3. Laden with that which is weighty; encumbered; burdened;
      bowed down, either with an actual burden, or with care,
      grief, pain, disappointment.
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            The heavy [sorrowing] nobles all in council were.
                                                  --Chapman.
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            A light wife doth make a heavy husband. --Shak.
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   4. Slow; sluggish; inactive; or lifeless, dull, inanimate,
      stupid; as, a heavy gait, looks, manners, style, and the
      like; a heavy writer or book.
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            Whilst the heavy plowman snores.      --Shak.
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            Of a heavy, dull, degenerate mind.    --Dryden.
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            Neither [is] his ear heavy, that it can not hear.
                                                  --Is. lix. 1.
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   5. Strong; violent; forcible; as, a heavy sea, storm,
      cannonade, and the like.
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   6. Loud; deep; -- said of sound; as, heavy thunder.
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            But, hark! that heavy sound breaks in once more.
                                                  --Byron.
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   7. Dark with clouds, or ready to rain; gloomy; -- said of the
      sky.
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   8. Impeding motion; cloggy; clayey; -- said of earth; as, a
      heavy road, soil, and the like.
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   9. Not raised or made light; as, heavy bread.
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   10. Not agreeable to, or suitable for, the stomach; not
       easily digested; -- said of food.
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   11. Having much body or strength; -- said of wines, or other
       liquors.
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   12. With child; pregnant. [R.]
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   Heavy artillery. (Mil.)
       (a) Guns of great weight or large caliber, esp. siege,
           garrison, and seacoast guns.
       (b) Troops which serve heavy guns.

   Heavy cavalry. See under Cavalry.

   Heavy fire (Mil.), a continuous or destructive cannonading,
      or discharge of small arms.

   Heavy metal (Mil.), large guns carrying balls of a large
      size; also, large balls for such guns.

   Heavy metals. (Chem.) See under Metal.

   Heavy weight, in wrestling, boxing, etc., a term applied to
      the heaviest of the classes into which contestants are
      divided. Cf. Feather weight
       (c), under Feather.
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   Note: Heavy is used in composition to form many words which
         need no special explanation; as, heavy-built,
         heavy-browed, heavy-gaited, etc.
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WordNet (r) 3.0 (2006):

heavy metal
    n 1: a metal of relatively high density (specific gravity
         greater than about 5) or of high relative atomic weight
         (especially one that is poisonous like mercury or lead)
    2: loud and harsh sounding rock music with a strong beat; lyrics
       usually involve violent or fantastic imagery [syn: heavy
       metal, heavy metal music]

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

heavy metal
 n.

    [Cambridge] Syn. big iron.


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

big iron
heavy metal

    (Or "heavy metal [Cambridge]) Large, expensive,
   ultra-fast computers.  Used generally of number crunching
   supercomputers such as Crays, but can include more
   conventional big commercial IBMish mainframes.  The term
   implies approval, in contrast to "dinosaur".

   [Jargon File]

   (2000-11-09)