According to WebMD:
Synesthesia is when you hear music, but you see shapes. Or you hear a word or a name and instantly see a color. Synesthesia is a fancy name for when you experience one of your senses through another. … It translates to “perceive together.” People who have this ability are called synesthetes.
My thoughts:
While first experiencing a certain smell, a certain taste, seeing a specific shape or shade, something else took place where as a child you picked up on wind blowing, feeling something, hearing a certain song or what have you where two or more senses simultaneously morphed into a combination of sensations leaving an imprint where triggers bring back the essence of that experience with the trigger being related to just one of the senses.