'Sumptuous' describes something so rich and beautiful that you can see the money in it — and enjoy it. A sumptuous meal has many dishes, each one good. A sumptuous room has heavy curtains, deep carpets, gold on the walls. A sumptuous fabric is thick and soft and shines a little. The word covers two ideas at once: great cost, and great pleasure to the senses. That second half matters, because it separates 'sumptuous' from words like 'expensive' (which is only about price) and from 'flashy' or 'showy' (which say the money is being waved in your face). 'Sumptuous' is admiring. It is a written, slightly formal word — you meet it in food writing, travel writing, reviews of films and costume dramas, and descriptions of hotels and palaces. Ordinary conversation prefers 'gorgeous', 'amazing', or 'really fancy'. A related word, 'sumptuary', looks similar but is quite different: sumptuary laws were old rules limiting how much people could spend on clothes and feasts, and you may see it in history books. If a writer calls something sumptuous, the writer likes it; if they wanted to criticise the spending, they would choose 'extravagant' or 'lavish' in a sour tone.