the conduct or procedure required by good breeding or prescribed by authority to be observed in social or official life
From Merriam-Webster: One definition of the French word étiquette is "ticket" or "label attached to something for identification." In 16th-century Spain, the French word was borrowed (and altered to "etiqueta") to refer to the written protocols describing orders of precedence and behavior demanded of those who appeared in court. Eventually, "etiqueta" came to be applied to the court ceremonies themselves as well as the documents which outlined the requirements for them. Interestingly, this then led to French speakers of the time attributing the second sense of "proper behavior" to their "étiquette," and in the middle of the 18th century English speakers finally adopted both the word and the second meaning from the French.