Siamese twins (linguistics) conjoined twins from Siam. In the context of the English language, this word was first used and popularised by H. W. Fowler, a renowned lexicographer. The most common conjunctions used in a phrase that constitutes Siamese twins are "and" or "or." The structure of any Siamese twins phrase has words that are related in some way. The words constituting a Siamese twins phrase may be synonyms, antonyms, include alliterations or similar-sounding words that often rhyme. Other varieties of Siamese twins may also be possible. Examples below are split into various tables; some may belong in more than one table but
Monochorionic twins Monochorionic twins Monochorionic twins are monozygotic (identical) twins that share the same placenta. If the placenta is shared by more than two twins (see multiple birth), these are monochorionic multiples. Monochorionic twins occur in 0.3% of all pregnancies. 75% of monozygotic twin pregnancies are monochorionic; the remaining 25% are "dichorionic diamniotic". If the placenta divides, this takes place after the third day after fertilization. Monochorionic twins generally have two amniotic sacs (called Monochorionic-Diamniotic "MoDi"), but sometimes, in the case of monoamniotic twins (Monochorionic-Monoamniotic "MoMo"), they also share the same amniotic sac. Monoamniotic twins occur when the split takes place after