What was the major language spoken in most courts and diplomatic circles of Europe late seventeenth century?

The major language spoken in most courts and diplomatic circles of Europe in the late seventeenth century was French.

Here's why:

* French cultural dominance: France, under Louis XIV, was a dominant cultural and military power in Europe. French art, fashion, and literature were highly influential.

* Diplomatic prestige: French was the language of diplomacy. Treaties, official correspondence, and negotiations were often conducted in French.

* Royal courts: Many European courts adopted French as the language of the court, even in countries where French was not the native tongue. This was partly due to the influence of the French monarchy and partly because French was considered a sophisticated and elegant language.

While other languages were spoken, French was the most widely understood and used language in these circles.