noun (n)

• a fricative sound (especially as an expression of disapproval)(noun.event)

  Synonym:
  fizzle, hiss, hissing, hushing
  

  source: wordnet30
• pronunciation with a sibilant (hissing or whistling) sound(noun.communication)

  Synonym:
  assibilation
  

  source: wordnet30
• Utterance with a hissing sound; also, the sound itself; a hiss.(noun)

  source: webster1913