An outdated term describing identical twins that have not been completely separated at birth.
Twins born joined together at one or more body parts and often sharing a body part. Most Siamese twins can be separated surgically, the prognosis depending on the site of connection and the extent of shared organs. Also called conjoined twins.
Identical twins that are physically joined together at birth. The condition ranges from twins joined only by the umbilical blood vessels (allantoido-angiopagous twins) to those in whom conjoined heads or trunk are inseparable.
A culturally insensitive term for congenitally united twins. In some cases, the individuals are joined in a small area and are capable of activity, but the extent of union may be so great that survival is impossible. Nevertheless, modern surgical techniques have made it possible to separate infants who in the past would not have been expected to survive.