a condition or lifestyle of great comfort and ease, characterized by rich and expensive/extravagant features;
e.g. Many rich people live in luxury while the poor lie starving in the streets.
(noun)
something, often relatively expensive and/or uncommon, that is not essential to life/survival but that adds convenience, comfort, or pleasure and that is thus desirable;
e.g. This food item is a luxury, so use it carefully.