tropical depression

noun Meteorology.
  1. an atmospheric low-pressure system originating in the tropics, specifically, a tropical cyclone in which the maximum sustained wind speed is 38 miles per hour (62 kilometers per hour) or less.

Origin of tropical depression

1845–50; tropical + depression (in the sense “(low atmospheric pressure”)
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British Dictionary definitions for tropical depression

tropical depression

noun
  1. Caribbean an area of heavy rains and winds, the first stage in the development of a possible hurricane
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

tropical depression in Science

tropical depression

  1. A tropical cyclone having sustained surface winds less than 39 mi (63 km) per hour. See Note at cyclone.
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