Synesthesia

1. Synesthesia
is a neurologically-based condition 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.or color-graphemic synesthesia, letters or numbers are perceived as inherently colored while in ordinal linguistic personification, numbers, days of the week and months of the year evoke personalities.

2. Grapheme-color synesthesia
Letters or numbers which appear in color. 
3. Ordinal-linguistic personification   

  Numbers, days of the week and months of the year take on personalities. 

4. Number-form synesthesia

Numbers, days of the week and months of the year are seen in precise location in space. 

5. Sound-color synesthesia

Certain sound trigger the viewing of colors or simple shapes. 
6. Lexical-gustatory Synesthesia
Words cause specific taste sensations in the mouth.