An indulgence, something that's Elegant, Something that's very expensive and brings great ease and comfort. Sumptuous living. Something Rare and difficult to obtain.
To be on top of the world. The pleasure of being able to do anything and buy anything at any given time without having to worry about money issues. To be stress and care free of money and other valuable expenses.
Lying on a bed of silk and roses, face pressed against the pillow, boutique chocolates tumbling from your mouth, masterbating furiously, in a French Chalet.
Anything on the spectrum that is above the standard. Luxury can range from leather seats in an economy car to a private jet or a private island. The spectrum of luxury can have such a wide range because what may be luxury to one person might not be to another person. In general anything that is obtained to make life more comfortable or enjoyable, something greater than what is needed to survive, including alcohol.
I believe my car is a luxury car because it has leather seats, but your car is a luxury car also because it is very expensive and stylish.