noun, plural ac·tiv·i·ties.
- 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.
- the number of atoms of a radioactive substance that disintegrate per unit of time, usually expressed in curies.
- an organizational unit or the function it performs.
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
- the capacity of a substance to undergo chemical change
- 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
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.
- 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.