[ ak-tiv-i-tee ]
/ ækˈtɪv ɪ ti /

noun, plural ac·tiv·i·ties.

Nearby words

  1. active‐matrix,
  2. activin,
  3. activism,
  4. activist,
  5. activities,
  6. activize,
  7. acto,
  8. actomyosin,
  9. acton,
  10. actor

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. 2019

Examples from the Web for activity

British Dictionary definitions for activity


/ (ækˈtɪvɪtɪ) /

noun plural -ties

the state or quality of being active
lively action or movement
any specific deed, action, pursuit, etcrecreational 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, 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

Medicine definitions for activity


[ ăk-tĭvĭ-tē ]


A physiological process.
The presence of neurogenic electrical energy in electroencephalography.
An ideal concentration for which the law of mass action will apply perfectly.
The intensity of a radioactive source.
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.