Actor meaning : A person who performs, plays a part in a theatrical play or film. One who acts; a doer. One who takes part in a situation. An advocate or proctor in civil courts or causes. One who institutes a suit; plaintiff or complainant. (policy debate) One who enacts a certain policy action. The entity that performs a role (in use case analysis). (grammar) The most agent-like argument of a clause, e.g. 'the torpedo' in "The torpedo sank the boat" and "The torpedo fired".