au gratin

UK: /o ɡratɛ̃/

US: /oʊ ˈgrætən, oʊ ˈgrɑtən/

US: (ō grät′n, ō grat′n, ô grät′n, ô grat′n; Fr. ō gra tan′)

WordReference Random House Learner's Dictionary of American English © 2025

au grat•in /oʊ ˈgrætən, oʊ ˈgrɑtən/  adj. 

1. Food topped with buttered breadcrumbs, grated cheese, or both and browned in an oven or broiler:
   [after a noun] potatoes au gratin.

WordReference Random House Unabridged Dictionary of American English © 2025

au grat•in  (ō grät′n, ō grat′n, ô grät′n, ô grat′n; Fr. ō gra tan′), [Cookery.]

1. Food cooked or baked with a topping of either browned bread crumbs and butter or grated cheese, or with both.

• French: literally, with the scraping, i.e., the burnt part
• 1800–10

Collins Concise English Dictionary © HarperCollins Publishers::

au gratin / o ɡratɛ̃/ adjective

1. covered and cooked with browned breadcrumbs and sometimes cheese

Etymology: French, literally: with the grating