Should I use 'sell out crowds' or 'sold-out crowds'?

"The famous singer performed to sold-out/sell out crowds."

Thanks a lot.

anonymousShould I use 'sell out crowds' or 'sold-out crowds'?

Use "sellout". In British English, "sell-out" is probably better. Either way, the dictionaries don't seem to recognize the adjective, but that's neither here nor there. You can think of it as an attributive use of the noun; the crowds constituted sellouts.

You can't have sold-out crowds because it is the event that is sold out, not the people. Actually, it is the tickets that sell out, but we can stretch that far. The tickets sell until the box office is out of them. They sell out.

I have to say that "sellout crowds" sounds like advertising cliche.