activity āļāļ·āļāļāļ°āđāļĢ activity āļāļ·āļāļāļ°āđāļĢ The state of being active.Energetic action or movement; liveliness.A specified pursuit in which a person partakes. An educational process or procedure intended to stimulate learning through actual experience.The intensity of a radioactive source.The ability to take part in a chemical reaction.A physiological process: respiratory activity.