Having considerable or great extension downward, or in a direction viewed as analogous with downward.As measured from the point of view: extending far above; lofty: as, a deep sky.As measured from without inward: extending or entering far within; situated far within or toward the center.As measured from the front backward: long: as, a deep house; a deep lot.Having (a certain) extension as measured from the surface downward or from the front backward: as, a mine 1,000 feet deep; a case 12 inches long and 3 inches deep; a house 40 feet deep; a file of soldiers six deep.Immersed; absorbed; engrossed; wholly occupied: as,deep in figures.Closely involved or implicated.Hard to get to the bottom or foundation of; difficult to penetrate or understand; not easily fathomed; profound; abstruse.Sagacious; penetrating; profound: as, a man of deep insight.Artful; contriving; plotting; insidious; designing: as, he is a deep schemer.Grave in sound; low in pitch: as, the deep tones of an organ.Great in degree; intense; extreme; profound: as, deep silence; deep darkness; deep grief; a deep black.Muddy; boggy; having much loose sand or soil: applied to roads.Heartfelt; earnest; affecting.Profound; thorough.Late; advanced in time.In logic, signifying much; having many predicates. See depth, 9.n. That which is of great depth. Specificallyn. plural A deep channel near a town: as, Memel Deeps, Prussia; Boston Deeps, near Boston, England.n. A name given by geographers to well-marked depressions in the ocean-bed greater than two thousand fathoms.n. The sky; the unclouded heavens.n. In coal-mining, the lowest part of the mine, especially the portion lower than the bottom of the shaft, or the levels extending therefrom.n. Any abyss.n. Nautical, the distance in fathoms between two successive marks on a lead-line: used in announcing soundings when the depth is greater than the mark under water and less than the one above it: as, by the deep 4. See lead-line.n. That which is too profound or vast to be fathomed or comprehended; a profound mystery.n. Depth; distance downward or outward.n. The middle point; the point of greatest intensity; the culmination.Deeply.To become deep; deepen.To go deep; sink.