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 kings 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 thought 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. . Deep silence. . Deep sleep. . Deeper darkness. . Their deep poverty. . An attitude of deep respect. (Motley)
7. Strongly coloured; 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. The bass of heavens deep organ. (Milton)
9. Muddy; boggy; sandy; said of roads. The ways in that vale were very deep. (Clarendon) a deep line of operations, 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.
Origin: oe. Dep, deop, as. Deop; akin to D. Diep, g. Tief, Icel. Djpr, Sw. Diup, dan. Dyb, goth. Diups; fr. The root of E. Dip, dive. See dip, Dive.