The Dos and Don'ts of Siamese Twins

Today we're looking at Siamese twins, not the politically incorrect version of conjoined twins, but rather a linguistic concept that almost dictates your word usage. Have you ever wondered why you can say "dos and don'ts" yet not "dont's and dos", and why it would be so incredibly wrong to do so?

The term is named after original Siamese twins Chang and Eng Bunker, the conjoined twins from Siam who effectively popularised the condition and "inspired" the name used for the condition.

Mmm... peanut butter and jelly!

If you feel uncomfortable using the phrase "Siamese twins" in this day and age, then feel free to use any of the other, perhaps more acceptable, linguistic terms that include the word binomial, meaning "having two names". These irreversible binomials are expressions with two principal elements that can be nouns, adjectives, verbs, or adverbs, usually joined by a conjunction (and, or, nor, and but in most cases). Sometimes they are instead composed of the two words in isolation. Examples include "above and beyond", "peanut butter and jelly", and "rain or shine". There are even trinomials, such as "tall, dark and handsome" or "signed, sealed, delivered". 

Perhaps you've been thinking to yourself that a pre-existing relationship between words that can dictate their usage sounds familiar. If you were just about to say that this sounds a lot like a collocation, you would be right. Some Siamese twins are effectively a collocation so strong that it is effectively frozen, hence the term freezes being another more accurate and politically correct name for the phenomenon.

Though certain Siamese twins are indeed a collocation that is so unbreakable that reversing the order sounds almost disgusting, some are not collocations at all and instead are idioms that through regular use are ingrained into the lexicon of the language.

Given that Siamese twins are fixed, unchangeable, and therefore, always the same, they inevitably become clichés and catchphrases through overuse.

There are really no such things as the dos and don'ts of Siamese twins, as the only thing you can do is use them as they are and make sure you don't change them. That said, they are a fascinating phenomenon that we probably never give much thought and often overlook despite being almost innately aware of their existence and constraints.