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[ak-tiv-i-tee] /ækˈtɪv ɪ ti/
noun, plural activities.
the state or quality of being active:
There was not much activity in the stock market today. He doesn't have enough physical activity in his life.
a specific deed, action, function, or sphere of action:
social activities.
work, especially in elementary grades at school, that involves direct experience by the student rather than textbook study.
energetic activity; animation; liveliness.
a use of energy or force; an active movement or operation.
normal mental or bodily power, function, or process.
Physical Chemistry. the capacity of a substance to react, corrected for the loss of reactivity due to the interaction of its constituents.
  1. the number of atoms of a radioactive substance that disintegrate per unit of time, usually expressed in curies.
  2. radioactivity.
an organizational unit or the function it performs.
1520-30; (< Middle French) < Medieval Latin āctīvitās. See active, -ity
Related forms
nonactivity, noun, plural nonactivities.
preactivity, noun, plural preactivities.
superactivity, noun, plural superactivities. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for activity
  • Of course, the state's activity has been vast and important.
  • On the other, weak housing investment and high interest rates are likely to have restrained consumer activity.
  • The epithelium of the mamma differs according to the state of activity of the organ.
  • Based on their answers, they were put into five groups of varying activity levels from inactive to highly active.
  • They also pointed out that it's unlikely heat from the active phones was to blame for the changes in brain activity.
  • For the new study, researchers created special mice whose telomerase activity could be switched on and off.
  • Mergers and acquisitions activity continues to languish this year as the fallout from the economic crisis lingers.
  • The basis of her firing has to be other than alleged criminal activity.
  • Since then, however, there has been little activity.
  • Click for more great links related to this activity.
British Dictionary definitions for activity


noun (pl) -ties
the state or quality of being active
lively action or movement
any specific deed, action, pursuit, etc: recreational activities
the number of disintegrations of a radioactive substance in a given unit of time, usually expressed in curies or disintegrations per second
  1. the capacity of a substance to undergo chemical change
  2. the effective concentration of a substance in a chemical system. The absolute activity of a substance B, λB, is defined as exp (μBRT) where μB is the chemical potential
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
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Word Origin and History for activity

c.1400, "active or secular life," from Old French activité, from Medieval Latin activitatem (nominative activitas), a word in Scholastic philosophy, from Latin activus (see active). Meaning "state of being active, briskness, liveliness" recorded from 1520s; that of "capacity for acting on matter" is from 1540s.

Online Etymology Dictionary, © 2010 Douglas Harper
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activity in Medicine

activity ac·tiv·i·ty (āk-tĭv'ĭ-tē)

  1. A physiological process.

  2. The presence of neurogenic electrical energy in electroencephalography..

  3. An ideal concentration for which the law of mass action will apply perfectly.

  4. The intensity of a radioactive source.

  5. The ability to take part in a chemical reaction.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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