Definitions of Melodrama on the Web:                            

• A play characterized by stereotypical characters, exaggerated emotions, and simplistic conflict.
  www.northern.edu/benkertl/drama_dictionary.html
• plays with elaborate but oversimplified plots, flat characters, excessive sentiment, and happy endings
  wps.ablongman.com/wps/media/objects/130/133428/glossary.html
• a film or literary work marked by "good guys" vs. "bad guys," unexpected plot twists, surprise endings, action and suspense. Examples: Most horror movies and detective thrillers.
  www.depaul.edu/~dsimpson/awtech/lexicon.html
• Originally a term for musical theatre, by the nineteenth century this became the designation of a suspenseful, plot-oriented drama featuring all-good heroes, all-bad villains, simplistic dialogue, soaring moral conclusions, and bravura acting.
  highered.mcgraw-hill.com/sites/0767430077/student_view0/glossary.html
• Exciting, emotional story. Often unsubtle and romantic.
  www.fisicx.com/quickreference/art/literature_glossary.html
• the dramatic genre characterized by an emphasis on plot over characterization; typically, characters are defined as heroes or villains, conflicts are defined along moral lines, and the resolution rewards the good and punishes the wicked. Spectacle and action are important to the melodramatic effect.
  filmplus.org/thr/dic4.html
• n. a play in which there are so much violence, feelings and exaggerations that it does not seem to be true.
  station05.qc.ca/csrs/bouscol/anglais/book_report/glossary3.html
• A play which suspends the audience through action and tension but contains the conventional "happy ending."
  www.bucks.edu/tutor/literms.html
• is a rigidly conventionalized genre of popular drama, theatrical rather than literary in appeal, characterized by rapid and exciting physical action, sharply contrasted and simplified characters, and colorful alternations of violence, pathos, and humor. The central situation in melodrama--victimization of helpless innocence by powerful evil forces--gives rise to four basic characters: the hero and the heroine, a comic ally who assists them, and the villain against whom they are pitted. ...
  www.pitt.edu/~gillis/dance/glossary.html
• an extravagant comedy in which action is more salient than characterization
  wordnet.princeton.edu/perl/webwn
• A melodrama in a more neutral and technical sense of the term is a play, film, or other work in which plot and action are emphasised in comparison to the more character-driven emphasis within a drama. Melodramas can be distinguished from tragedy by the fact that it is open to having a happy ending.
  en.wikipedia.org/wiki/Melodrama