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.