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activity

[ak-tiv-i-tee]
noun, plural ac·tiv·i·ties.
  1. 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.
  2. a specific deed, action, function, or sphere of action: social activities.
  3. work, especially in elementary grades at school, that involves direct experience by the student rather than textbook study.
  4. energetic activity; animation; liveliness.
  5. a use of energy or force; an active movement or operation.
  6. normal mental or bodily power, function, or process.
  7. Physical Chemistry. the capacity of a substance to react, corrected for the loss of reactivity due to the interaction of its constituents.
  8. Physics.
    1. the number of atoms of a radioactive substance that disintegrate per unit of time, usually expressed in curies.
    2. radioactivity.
  9. an organizational unit or the function it performs.
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Origin of activity

1520–30; (< Middle French) < Medieval Latin āctīvitās. See active, -ity
Related formsnon·ac·tiv·i·ty, noun, plural non·ac·tiv·i·ties.pre·ac·tiv·i·ty, noun, plural pre·ac·tiv·i·ties.su·per·ac·tiv·i·ty, noun, plural su·per·ac·tiv·i·ties.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for activity's

activity

noun plural -ties
  1. the state or quality of being active
  2. lively action or movement
  3. any specific deed, action, pursuit, etcrecreational activities
  4. 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, λ B, is defined as exp (μ B RT) where μ B is the chemical potential
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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 activity's

activity

n.

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.

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Online Etymology Dictionary, © 2010 Douglas Harper

activity's in Medicine

activity

(ăk-tĭvĭ-tē)
n.
  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.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.