siamese, n. & adj.
--n. (pl. same)
1 a a native of Siam (now Thailand) in SE Asia. b the language of Siam.
2 (in full Siamese cat) a a cat of a cream-coloured short-haired breed with a brown face and ears and blue eyes. b this breed.
--adj. of or concerning Siam, its people, or language.
Siamese twins
1 twins joined at any part of the body and sometimes sharing organs etc.
2 any closely associated pair.