Lust is a strong craving for sex. It also can mean a hunger for anything, like lust for power.
While lust isn't a dirty word, it is a strong word. You don't have lust for something you don't really care about. Lust is a strong, powerful desire, whether it's a noun or verb: you lust for things you deeply crave. Someone greedy lusts for money. Someone gluttonous lusts for food. The most basic meaning of lust is an unquenchable desire for sex, but people lust for all sorts of things.
