Siamese twins (linguistics) Siamese twins (linguistics) Siamese twins (also irreversible binomials, binomials, binomial pairs, nonreversible word pairs, or freezes) in the context of the English language refer to a pair or group of words used together as an idiomatic expression or collocation, usually conjoined by the words "and" or "or". The order of elements cannot be reversed. The expressions "milk and honey" (two nouns), "short and sweet" (two adjectives), and "do or die" (two verbs) are various examples of Siamese twins. Many Siamese twins are "catchy" (and thus clichés and catchphrases) due to alliteration, rhyming, or their ubiquity in society and culture. Word
Monoamniotic twins Monoamniotic twins Monoamniotic twins are identical twins that share the same amniotic sac within their mother’s uterus. Monoamniotic twins are always identical, always monochorionic and are usually termed Monoamniotic-Monochorionic ("MoMo" or "Mono Mono") twins. They also share the placenta, but have two separate umbilical cords. Monoamniotic twins develop when an embryo does not split until after formation of the amniotic sac, at about 9-13 days after fertilization. Monoamniotic triplets or other monoamniotic multiples are possible, but extremely rare. Other obscure possibilities include multiples sets where monoamniotic twins are part of a larger gestation such as triplets, quadruplets, or more. Monoamniotic