Dictionary:

melodramatic

  (mĕl'ə-drə-măt'ĭk)

1. Having the excitement and emotional appeal of melodrama: “a melodramatic account of two perilous days spent among the planters” (Frank O. Gatell).
2. Exaggeratedly emotional or sentimental; histrionic: “Accuse me, if you will, of melodramatic embroidery” (Erskine Childers).
3. Characterized by false pathos and sentiment.

adjective

Suggesting drama or a stage performance, as in emotionality or suspense: dramatic, histrionic, histrionical, sensational, spectacular, theatric, theatrical. See excite/bore/interest, style/good style/bad style, surprise/expect.

Definition: extravagant in speech, behavior
Antonyms: calm, normal, untheatrical

The adjective has 2 meanings:

Meaning #1: having the excitement and emotional appeal of melodrama

Meaning #2: characteristic of acting or a stage performance; often affected
  Synonym: histrionic