Synesthesia is a neurological phenomenon in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway.

Synesthesia (also spelled synæsthesia or synaesthesia; from the Ancient Greek σύν syn, "together", and αἴσθησις aisthēsis, "sensation") is a neurological phenomenon in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. People who report such experiences are known as synesthetes.
Forms of Synesthesia:

  • Grapheme-color synesthesia
  • Chromesthesia
  • Spatial sequence synesthesia
  • Number form
  • Auditory-tactile synesthesia
  • Misophonia
  • Mirror-touch synesthesia
  • Lexical-gustatory synesthesia

There are many more other forms of synesthesia.