depression

1. In general, a point or limited area of locally lower elevation in a particular surface.
2. In meteorology, an area of low pressure; a low or trough.
   This is usually applied to a certain stage in the development of a tropical cyclone, to migratory lows and troughs, and to upper-level lows and troughs that are only weakly developed. This use of the term is most common in the European literature.
   See V-shaped depression.
   
3. 
   Same as depression angle.
   
4. 
   See wet-bulb depression, dewpoint spread.

1. A type of stress characterized by uniformity in all directions.