by-your-leave

The phrase "by your leave" originates from the 16th century as a courteous formula, literally meaning "with your permission." It is a direct calque of the French construction avec votre permission. The expression fossilized into a hyphenated noun in the 19th century, encapsulating the concept of a formal, often sarcastically noted, request or apology for an intrusion. Its evolution from a spoken courtesy to a lexicalized unit demonstrates how syntactic phrases can become fixed idioms, carrying the social etiquette of a past era into modern usage as a singular concept.

This is a fixed phrase functioning as a compound noun. It is not productively formed from separable modern morphemes but is a fossilized expression from Early Modern English syntax.