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

(obsolete, law) Someone who institutes a legal suit; a plaintiff or complainant. / (obsolete) Someone acting on behalf of someone else; a guardian.

A radioactive, metallic chemical element (symbol: Ac) with an atomic number of 89; found in uranium ores.

A female who performs on the stage or in films. / (now rare) A female doer or "actor" (in a general sense).

That can be acted on; that can be used as the basis for taking action. / (law) Affording grounds for legal action.

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

(modal) In act or in fact; really; in truth; positively. / (obsolete) Actively.

(chiefly theology) relating to a person's acts or deeds; active, practical / Existing in reality, not just potentially; really acted or acting; occurring in fact.

(finance) something actually received; real receipts, as distinct from estimated ones.

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.