AU GRATIN Meaning of AU GRATIN in English [ əʊ'grata~ ]■ adjective [ postposition \] sprinkled with breadcrumbs or grated cheese and browned.OriginFr., lit. 'by grating', from gratter 'to grate'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004