Source : Webster's Revised Unabridged Dictionary (1913)

Light \Light\ (l[imac]t), n. [OE. light, liht, AS. le['o]ht;
   akin to OS. lioht, D. & G. licht, OHG. lioht, Goth.
   liuha[thorn], Icel. lj[=o]s, L. lux light, lucere to shine,
   Gr. leyko`s white, Skr. ruc to shine. [root]122. Cf. {Lucid},
   {Lunar}, {Luminous}, {Lynx}.]
   1. That agent, force, or action in nature by the operation of
      which upon the organs of sight, objects are rendered
      visible or luminous.

   Note: Light was regarded formerly as consisting of material
         particles, or corpuscules, sent off in all directions
         from luminous bodies, and traversing space, in right
         lines, with the known velocity of about 186,300 miles
         per second; but it is now generally understood to
         consist, not in any actual transmission of particles or
         substance, but in the propagation of vibrations or
         undulations in a subtile, elastic medium, or ether,
         assumed to pervade all space, and to be thus set in
         vibratory motion by the action of luminous bodies, as
         the atmosphere is by sonorous bodies. This view of the
         nature of light is known as the undulatory or wave
         theory; the other, advocated by Newton (but long since
         abandoned), as the corpuscular, emission, or Newtonian
         theory. A more recent theory makes light to consist in
         electrical oscillations, and is known as the
         electro-magnetic theory of light.

   2. That which furnishes, or is a source of, light, as the
      sun, a star, a candle, a lighthouse, etc.

            Then he called for a light, and sprang in. --Acts
                                                  xvi. 29.

            And God made two great lights; the greater light to
            rule the day, and the lesser light to rule the
            night.                                --Gen. i. 16.

   3. The time during which the light of the sun is visible;
      day; especially, the dawn of day.

            The murderer, rising with the light, killeth the
            poor and needy.                       --Job xxiv.
                                                  14.

   4. The brightness of the eye or eyes.

            He seemed to find his way without his eyes; For out
            o' door he went without their helps, And, to the
            last, bended their light on me.       --Shak.

   5. The medium through which light is admitted, as a window,
      or window pane; a skylight; in architecture, one of the
      compartments of a window made by a mullion or mullions.

            There were windows in three rows, and light was
            against light in three ranks.         --I Kings
                                                  vii.4.

   6. Life; existence.

            O, spring to light, auspicious Babe, be born!
                                                  --Pope.

   7. Open view; a visible state or condition; public
      observation; publicity.

            The duke yet would have dark deeds darkly answered;
            he would never bring them to light.   --Shak.

   8. The power of perception by vision.

            My strength faileth me; as for the light of my eyes,
            it also is gone from me.              --Ps. xxxviii.
                                                  10.

   9. That which illumines or makes clear to the mind; mental or
      spiritual illumination; enlightenment; knowledge;
      information.

            He shall never know That I had any light of this
            from thee.                            --Shak.

   10. Prosperity; happiness; joy; felicity.

             Then shall thy light break forth as the morning,
             and thy health shall spring forth speedily. --Is.
                                                  lviii. 8.

   11. (Paint.) The manner in which the light strikes upon a
       picture; that part of a picture which represents those
       objects upon which the light is supposed to fall; the
       more illuminated part of a landscape or other scene; --
       opposed to {shade}. Cf. {Chiaroscuro}.

   12. Appearance due to the particular facts and circumstances
       presented to view; point of view; as, to state things
       fairly and put them in the right light.

             Frequent consideration of a thing . . . shows it in
             its several lights and various ways of appearance.
                                                  --South.

   13. One who is conspicuous or noteworthy; a model or example;
       as, the lights of the age or of antiquity.

             Joan of Arc, A light of ancient France. --Tennyson.

   14. (Pyrotech.) A firework made by filling a case with a
       substance which burns brilliantly with a white or colored
       flame; as, a Bengal light.

   Note: Light is used figuratively to denote that which
         resembles physical light in any respect, as
         illuminating, benefiting, enlightening, or enlivening
         mankind.

   {Ancient lights} (Law), {Calcium light}, {Flash light}, etc.
      See under {Ancient}, {Calcium}, etc.

   {Light ball} (Mil.), a ball of combustible materials, used to
      afford light; -- sometimes made so as to be fired from a
      cannon or mortar, or to be carried up by a rocket.

   {Light barrel} (Mil.), an empty powder barrel pierced with
      holes and filled with shavings soaked in pitch, used to
      light up a ditch or a breach.

   {Light dues} (Com.), tolls levied on ships navigating certain
      waters, for the maintenance of lighthouses.

   {Light iron}, a candlestick. [Obs.]

   {Light keeper}, a person appointed to take care of a
      lighthouse or light-ship.

   {Light money}, charges laid by government on shipping
      entering a port, for the maintenance of lighthouses and
      light-ships.

   {The light of the countenance}, favor; kindness; smiles.

            Lord, lift thou up the light of thy countenance upon
            us.                                   --Ps. iv. 6.

   {Northern lights}. See {Aurora borealis}, under {Aurora}.

   {To bring to light}, to cause to be disclosed.

   {To come to light}, to be disclosed.

   {To see the light}, to come into the light; hence, to come
      into the world or into public notice; as, his book never
      saw the light.

Calcium \Cal"ci*um\ (k[a^]l"s[i^]*[u^]m), n. [NL., from L. calx,
   calcis, lime; cf F. calcium. See {Calx}.] (Chem.)
   An elementary substance; a metal which combined with oxygen
   forms lime. It is of a pale yellow color, tenacious, and
   malleable. It is a member of the alkaline earth group of
   elements. Atomic weight 40. Symbol Ca.

   Note: Calcium is widely and abundantly disseminated, as in
         its compounds calcium carbonate or limestone, calcium
         sulphate or gypsum, calcium fluoride or fluor spar,
         calcium phosphate or apatite.

   {Calcium light}, an intense light produced by the
      incandescence of a stick or ball of lime in the flame of a
      combination of oxygen and hydrogen gases, or of oxygen and
      coal gas; -- called also {Drummond light}.

Source : WordNet®

calcium light
     n : a lamp consisting of a flame directed at a cylinder of lime
         with a lens to concentrate the light; formerly used for
         stage lighting [syn: {limelight}]