lust

Definition:

Lust is a very strong desire, usually in the context of wanting something sinful or immoral. To lust is to have lust.

In the Bible, "lust" usually referred to sexual desire for someone other than one's own spouse.
Sometimes this term was used in a figurative sense to refer to worshiping idols.
Depending on the context, "lust" could be translated as "wrong desire" or "strong desire" or "wrongful sexual desire" or "strong immoral desire" or "to strongly desire to sin."
The phrase "to lust after" could be translated as "to wrongly desire" or "to think immorally about" or "to immorally desire."