activity >> /ækˈtɪvədi/
Definition: [noun] The condition in which things are happening or being done.
Example: there has been a sustained level of activity in the economy
Definition: [noun] A thing that a person or group does or has done.
Example: the firm's marketing activities
Definition: [noun] A thermodynamic quantity representing the effective concentration of a particular component in a solution or other system, equal to its concentration multiplied by an activity coefficient.