Meaning

noun open pastry filled with fruit or custard

originBorrowed around 1846 from French flan (“cheesecake, custard tart, flan”), or in some uses (in reference to Spanish/Latin American flans) later from Spanish flan (itself from the French), both from Old French flaon (whence also Middle English flaon, flaun (“pie; cake”)), from Late Latin fladō (“flat cake”), from Frankish *flaþō (“flat cake”), from Proto-Indo-European *pleth₂- (“broad, flat”);…

Etymology from Wiktionary, CC BY-SA 3.0