Marquis \Mar"quis\, n. [F. marquis, OF. markis, marchis, LL. marchensis; of German origin; cf. G. mark bound, border, march, OHG. marcha. See March border, and cf. Marchioness, Marquee, Marquess.]

A nobleman in England, France, and Germany, of a rank next below that of duke. Originally, the marquis was an officer whose duty was to guard the marches or frontiers of the kingdom. The office has ceased, and the name is now a mere title conferred by patent.

Source: Webster's Revised Unabridged Dictionary (1913)