radioactive fallout


or fall-out

  1. the settling to the ground of airborne particles ejected into the atmosphere from the earth by explosions, eruptions, forest fires, etc., especially such settling from nuclear explosions (radioactive fallout).Compare rainout.
  2. the particles themselves.Compare rainout.
  3. an unexpected or incidental effect, outcome, or product: the psychological fallout of being obese.
  4. effects; results: emotional fallout from a divorce.

Origin of fallout

First recorded in 1945–50; noun use of verb phrase fall out Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for radioactive fallout


  1. the descent of solid material in the atmosphere onto the earth, esp of radioactive material following a nuclear explosion
  2. any solid particles that so descend
  3. informal side-effects; secondary consequences
verb fall out (intr, adverb)
  1. informal to quarrel or disagree
  2. (intr) to happen or occur
  3. military to leave a parade or disciplinary formation
sentence substitute
  1. military the order to leave a parade or disciplinary formation
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

Word Origin and History for radioactive fallout



"radioactive particles," 1950, from fall (v.) + out (adv.).

Online Etymology Dictionary, © 2010 Douglas Harper