Linguaphile wrote: crac
[economic] crash, [stock market] crash
It also means something like star, champion, pro. E.g. I remember when I bought one of the sports newspapers in Catalonia, they repeatedly called Ronaldinho (yes, it's been some time) "el crack".
Speaking of a(n) (economic) crash, French uses krach
for that while it's definitely not used in Germany any more (we use crash
instead). It seems several languages loaned it from German