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

Profound; thorough; complete; unmixed; intense; heavy; heartfelt; as, deep distress; deep melancholy; deep horror.

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

That which is profound, not easily fathomed, or incomprehensible; a moral or spiritual depth or abyss.

the central and most intense or profound part; "in the deep of night"; "in the deep of winter"

(of darkness) very intense; "thick night"; "thick darkness"; "a face in deep shadow"; "deep night"

of an obscure nature; "the new insurance policy is written without cryptic or mysterious terms"; "a deep dark secret"; "the inscrutible workings of Providence"; "in its mysterious past it encompasses all the dim origins of life"- Rachel Carson; "rituals totally mystifying to visitors from other lands"

difficult to penetrate; incomprehensible to one of ordinary understanding or knowledge; "the professor's lectures were so abstruse that students tended to avoid them"; "a deep metaphysical theory"; "some recondite problem in historiography"

to an advanced time; "deep into the night"; "talked late into the evening"

the distance in fathoms between two successive marks on a lead line, as "By the deep, four."