flan UK /flæn/US /flɑn/noun 4verb 1forms 3 noun4 •(US) A dessert of congealed custard, often topped with caramel, especially popular in Spanish-speaking countries. •(UK, Australia) A baked tart with a sweet or savoury filling in an open-topped pastry case.The menu includes a number of excellent fish dishes such as the […] broccoli flan. — 2004 •A coin die. •(informal, slang) A fan of the U.S. TV series Firefly.(some) Firefly flans call themselves Browncoats (Remember, the hot movie from Universal is out this September! :) — 2005 verb1 •To splay or bevel internally, as a window-pane. formsflanned · flanning · flans