Caviar is the salted eggs of certain large fish, especially sturgeon, eaten as a rare and expensive food. The eggs are small, often dark, and people take them in tiny amounts — on toast, with a small spoon, at a party where someone wants to show that the food is special. Because the real thing costs so much, the word itself carries a feeling of wealth and luxury. Cheaper fish eggs are sometimes sold under the same name, and people stretch the word for those too. It is a food name you meet on menus and in talk about fancy living, not a daily kitchen word for most families.