Merlot is a dark blue-colored wine grape variety, that is used as both a blending grape and for varietal wines. The name Merlot is thought to be a diminutive of merle, the French name for the blackbird, probably a reference to the color of the grape.erlot is also one of the most popular red wine varietals in many markets. This flexibility has helped to make it one of the world's most planted grape varieties.