Caramelized describes a food whose natural or added sugars have browned through heat, taking on the golden-to-deep-brown color and rich, toasted-sweet flavor of caramelization.
Cooks caramelize ingredients through searing, roasting, or grilling, where sustained high heat breaks down sugars into new flavor compounds. Onions are a classic example: slowly sautéed or roasted onions caramelize as their natural sugars brown, turning sweet, nutty, and mildly savory.
The term also describes browned crusts on bread and the torched sugar top of crème brûlée. "Caramelized" is not interchangeable with "seared": a seared surface may owe its browning mainly to the Maillard reaction (sugars reacting with proteins) rather than caramelization of sugar alone.