A parody (also called spoof, send-up or lampoon), in use, is an imitative work created to imitate, or comment on and trivialize an original work, its subject, author, style, or some other target, by means of satiric or ironic imitation.
Dallas Baptist University Excellent explanation of the ingredients of Parody in the theatre, offering examples of the genre thoughout history.
Gale Brief definition of Parody in a literary context.
Merriam-Webster Online Entry for Parody.
Northern Kentucky University Definition of Parody.
PBS Useful glossary of terms relating to various forms of humour, including Parody.