See more synonyms for activity on
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.

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··per·ac·tiv·i·ty, noun, plural su·per·ac·tiv·i·ties. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for activity

Contemporary Examples of activity

Historical Examples of activity

  • Early were hammers ringing on anvils in the Dragon Court, and all was activity.

    The Armourer's Prentices

    Charlotte M. Yonge

  • Its attributes of youth are the activity and eager life with which it is redundant.

    Sketches from Memory

    Nathaniel Hawthorne

  • The vigilance and activity of Nicias never relaxed for a moment.

  • His energy and activity throughout the march is described as intense.

  • Though wounded, they had retained their strength and activity in battle.



British Dictionary definitions for 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
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

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

activity in Medicine


  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.