Meaning of Siamese twins

Si'amese twins'

Pronunciation: [key]
  1. congenitally united twins, Chang and Eng (1811–74), born in Siam, who were joined to each other at the chest by a short, tubular, cartilaginous band.
  2. any twins who are born joined together in any manner.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.