Deep (dēp), a. [Compar.Deeper (?); superl.Deepest (?).] [OE. dep, deop, AS. deóp; akin to D. diep, G. tief, Icel. djūpr, 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.