Definitions for au gratinoʊ ˈgræt n, oʊ ˈgrɑt n; Fr. oʊ graˈtɛ̃
Random House Webster's College Dictionary
au grat•inoʊ ˈgræt n, oʊ ˈgrɑt n; Fr. oʊ graˈtɛ̃(adj.)
topped with buttered breadcrumbs or grated cheese or both and browned in an oven or broiler.
Origin of au gratin:
1800–10; < F: lit., with the scraping, i.e., the burnt part
cooked while covered with browned breadcrumbs (and sometimes cheese)