1.Definition: a betrayal of one's principles principles, country, cause, etc.

Category: General

2.Definition: an event for which all tickets are sold

"Get your tickets for the concert early, it is sure to be a sellout"

Category: General

3.Definition: someone who has sold out

Category: People

4.Definition: the selling of an entire stock of something

"The latest Xbox game is so popular, shops are warning of a probable sellout before Christmas"

Category: General