(Christianity) the abode of Satan and the forces of evil; where sinners suffer eternal punishment; "Hurl'd headlong...To bottomless perdition, there to dwell"- John Milton; "a demon from the depths of the pit"
a cause of difficulty and suffering; "war is hell"; "go to blazes"
any place of pain and turmoil; "the hell of battle"; "the inferno of the engine room"; "when you're alone Christmas is the pits";
a device for showing the operating condition of some system
a signal for attracting attention
(chemistry) a substance that changes color to indicate the presence of some ion or substance; can be used to indicate the completion of a chemical reaction or (in medicine) to test for a particular reaction
having a set of mutually perpendicular axes; meeting at right angles; "wind and sea may displace the ship's center of gravity along three orthogonal axes"; "a rectangular Cartesian coordinate system"
a set of techniques for exploring underlying motives and a method of treating various mental disorders; based on the theories of Sigmund Freud; "his physician recommended psychoanalysis"