IPA: /ˈsɛlaʊt/
KK: /ˈsɛlˌaʊt/
A situation where all tickets for an event are sold, meaning no more tickets are available.
The concert was a complete sellout, with every ticket purchased within hours.
Sellout → It is formed from "sell" (from Old English *sellan*, meaning to give or hand over) and "out" (meaning completely or entirely). The word "sellout" refers to the act of selling all available items or completely giving up one's principles for personal gain.
Think of the act of 'handing over' ('sell') everything 'completely' ('out') — that's why sellout means to sell everything or to give up one's values.
No commonly confused words.