From Old French estuver 'to steam, bathe' — originally meant a steam bath or brothel before it meant a cooked dish.
A dish of meat, vegetables, and stock cooked slowly in liquid.
From Old French estuver 'to bathe in steam, stew,' probably from Vulgar Latin *extūphāre, from ex- + Greek tȳphein 'to smoke, steam.' Originally meant a heated room (like a steam bath) or a brothel — the cooking sense came later, around the 15th century. Key roots: tȳphein (Greek: "to smoke, steam").