Source : Webster's Revised Unabridged Dictionary (1913)

Deep \Deep\ (d[=e]p), a. [Compar. {Deeper}; superl. {Deepest}.]
   [OE. dep, deop, AS. de['o]p; akin to D. diep, G. tief, Icel.
   dj[=u]pr, Sw. diup, Dan. dyb, Goth. diups; fr. the root of E.
   dip, dive. See {Dip}, {Dive}.]
   1. Extending far below the surface; of great perpendicular
      dimension (measured from the surface downward, and
      distinguished from high, which is measured upward); far to
      the bottom; having a certain depth; as, a deep sea.

            The water where the brook is deep.    --Shak.

   2. Extending far back from the front or outer part; of great
      horizontal dimension (measured backward from the front or
      nearer part, mouth, etc.); as, a deep cave or recess or
      wound; a gallery ten seats deep; a company of soldiers six
      files deep.

            Shadowing squadrons deep.             --Milton.

            Safely in harbor Is the king's ship in the deep
            nook.                                 --Shak.

   3. Low in situation; lying far below the general surface; as,
      a deep valley.

   4. Hard to penetrate or comprehend; profound; -- opposed to
      shallow or superficial; intricate; mysterious; not
      obvious; obscure; as, a deep subject or plot.

            Speculations high or deep.            --Milton.

            A question deep almost as the mystery of life. --De
                                                  Quincey.

            O Lord, . . . thy thoughts are very deep. --Ps.
                                                  xcii. 5.

   5. Of penetrating or far-reaching intellect; not superficial;
      thoroughly skilled; sagacious; cunning.

            Deep clerks she dumbs.                --Shak.

   6. Profound; thorough; complete; unmixed; intense; heavy;
      heartfelt; as, deep distress; deep melancholy; deep
      horror. ``Deep despair.'' --Milton. ``Deep silence.''
      --Milton. ``Deep sleep.'' --Gen. ii. 21. ``Deeper
      darkness.'' -->Hoole. ``Their deep poverty.'' --2 Cor.
      viii. 2.

            An attitude of deep respect.          --Motley.

   7. Strongly colored; dark; intense; not light or thin; as,
      deep blue or crimson.

   8. Of low tone; full-toned; not high or sharp; grave; heavy.
      ``The deep thunder.'' --Byron.

            The bass of heaven's deep organ.      --Milton.

   9. Muddy; boggy; sandy; -- said of roads. --Chaucer.

            The ways in that vale were very deep. --Clarendon.

   {A deep line of operations} (Military), a long line.

   {Deep mourning} (Costume), mourning complete and strongly
      marked, the garments being not only all black, but also
      composed of lusterless materials and of such fashion as is
      identified with mourning garments.

Mourning \Mourn"ing\, n. [AS. murnung.]
   1. The act of sorrowing or expressing grief; lamentation;
      sorrow.

   2. Garb, drapery, or emblems indicative of grief, esp.
      clothing or a badge of somber black.

            The houses to their tops with black were spread, And
            ev'n the pavements were with mourning hid. --Dryden.

   {Deep mourning}. See under {Deep}.