The Webbie definition of “bascule” identifies it as a word from the French language and refers to a type of bridge. The first definition of the word in French dictionaries, like the Webster definition, describes a mechanism which is balanced upon a pivotal point and which raises one end by lowering the other.

A quick check of later editions of Mr. Webster’s dictionary (1934 – 1950 – 1957 – 1993) reveals that the English meaning of the word has not changed drastically down through the years. The French, however, have expanded the original meaning to describe a seesaw action of objects other than bridges. Basculer is the French verb to describe an “alternate movement in a contrary sense”; basculeur is something or someone who moves in this fashion.

A bridge can bascule. So can an armchair. A scale (balance in French) can be a pair of scales such as used by a pharmacist or the blindfolded figure of Justice, which operates on this motion. A light switch, or toggle, is a basculeur. A person who cannot decide and swings from one choice to another is said to bascule. A form of politics, Politique de bascule, is to swing between opposing parties. Bascule refers to an electronic system which takes one of two possible states (0 or 1). This is called a relation binaire.

The root of this word is perhaps even more interesting than any of the above. Bascule appeared in the French language in the 15th century as a noun (m.), bacul , meaning the part of a horse’s harness known today as a “crupper”, a leather strap passing under the horse’s tail for the purpose of stopping the animal from rearing up. An earlier 11th century word, croupière, is still in use today to describe this bit of equine wardrobe, but bacul quickly changed.

The syllables of the word, “ba” and “cul” came from battre, to beat or strike (frapper), and cul, the postérieur, the part of the anatomy known in English-speaking countries as “arse” or “ass”. Mon cul ! is a popular vulgarity in France today, and reams could be written on variations of this word which evolved since it first appeared in the 13th century, words as diverse as cul-de-sac and cul-blanc, one of the petrel family.

In less than 100 years, bacul, however, became bascule and was being used in reference to the seesaw motion described in our very own Webster 1913.

Source: “Le Petit Robert”, ISBN 2-85936-186-O