Definition of Craniopagus parasiticus

Craniopagus parasiticus: Conjoined twins joined at the head (craniopagus) in which a rudimentary head (with little or no body) is attached to the head of the larger and usually more normal twin. The rudimentary head was thought to be parasitic.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=26735
Last Editorial Review: 6/14/2012