Depression /(?)/

De·pres·sion

Depression

n.
  1. The act of depressing.
  2. The state of being depressed; a sinking.
  3. A falling in of the surface; a sinking below its true place; a cavity or hollow; as, roughness consists in little protuberances and depressions.
  4. Humiliation; abasement, as of pride.
  5. Dejection; despondency; lowness.
    In a great depression of spirit.
    — Baker.
  6. Diminution, as of trade, etc.; inactivity; dullness.
  7. The angular distance of a celestial object below the horizon. (Astron.)
  8. The operation of reducing to a lower degree; -- said of equations. (Math.)
  9. A method of operating for cataract; couching. See Couch, v. t., 8. (Surg.)

Phrases & Compounds
Angle of depression
one which a descending line makes with a horizontal plane.
Depression of the dewpoint
the number of degrees that the dew-point is lower than the actual temperature of the atmosphere.
Depression of the pole
its apparent sinking, as the spectator goes toward the equator.
Depression of the visible horizon
Same as Dip of the horizon, under Dip.