Definition of Synesthesia

Synesthesia: A condition in which normally separate senses are not separate. Sight may mingle with sound, taste with touch, etc. The senses are cross-wired. For example, when a digit-color synesthete sees or just thinks of a number, the number appears with a color film over it. A given number's color never changes; it appears every time with the number. Synesthesia can take many forms. A synesthete may sense the taste of chicken as a pointed object. Other synesthetes hear colors. Still others may have several senses cross-wired.

Estimates of the frequency of synesthesia range from 1 in 250,000 to 1 in 2,000. People with synesthesia are 6 times more likely to be female than male. Most synesthetes find their unusual sensory abilities enjoyable.

People with synesthesia often report that one or more of their family members also have synesthesia, so it may in at least some cases be an inherited condition.

It may be that synesthesia arises when particular senses fail to become fully independent of one another during normal development. According to this school of thought, all babies are synesthetes. Synesthesia can be induced by certain hallucinogenic drugs and can also occur in some types of seizure disorders.

The words synesthesia is a hybrid of Latin and Greek -- the Latin syn- (together) + -esthesia, from the Greek aisthesis (sensation or perception).