(uncountable) The state or quality of being active; activeness. / (countable) Something done as an action or a movement.

(transitive) To encourage development or induce increased activity; to stimulate.

In an active manner. / (grammar) In the active form; not passive.

Having the power or quality of acting; causing change; communicating action or motion; acting;—opposed to passive, that receives. / Quick in physical movement; of an agile and vigorous body; nimble.

A person or thing that is acting or capable of acting. / (electronics) Any component that is not passive. See Passivity (engineering).

Making active and effective; bringing into a state of activity. / (physics) The process of making a radioisotope by bombarding a stable element with neutrons or protons.

plural of activity

The practice of using action to achieve a result, such as political demonstration or a strike in support of or in opposition to an issue.

Third-person singular simple present indicative form of activate

One who, or that which, activates. / (chemistry) Something that activates a catalyst / (biology) Any chemical or agent which regulates one or more genes by increasing the rate of transcription.