The condition or quality of being deep. The extent, measurement, or dimension downward, backward, or inward: dove to a depth of 30 feet; shelves with enough depth to store the large boxes. The measurement or sense of distance from an observation point, such as linear perspective in painting. often A deep part or place: the ocean depths; in the depths of the forest. The most profound or intense part or stage: the depth of despair; an experience that touched the depths of tragedy. Intensity; force: had not realized the depth of their feelings for one another. The severest or worst part: in the depth of an economic depression. A low point, level, or degree: Production has fallen to new depths. Intellectual complexity or penetration; profundity: a novel of great depth. The range of one's understanding or competence: I am out of my depth when it comes to cooking. Strength held in reserve, especially a supply of skilled or capable replacements: a team with depth at every position. The degree of richness or intensity: depth of color. Lowness in pitch. Complete detail; thoroughness: the depth of her research; an interview conducted in great depth.