Rembrandt is the name of a Dutch painter, Rembrandt van Rijn, who lived from 1606 to 1669. People who care about art often put him among the greatest painters in Europe. He painted many pictures of people — including many of his own face — and many pictures of religious stories. What most people notice first is how he used light and dark: a face or a hand can shine while the rest of the room falls into shadow. When someone says “a Rembrandt,” they usually mean a painting by him. More loosely, they may mean a portrait that feels rich and full of light and dark in that same way. It is a person’s name, not an everyday word you use for other things. You capitalise it, and you meet it in museums, art class, and books about painting, not in ordinary small talk.