Indian Railway uses various acronyms on its site for ticket status, here are the full forms of commonly used acronyms
RAC: Reservation Against Cancellation
When the quota for reserved seats get filled (for 9 sleeper train, the available sleeper tickets will be 9x72), RAC list starts which means that the person having RAC ticket will be allowed to board the train. Most often, the RAC tickets get confirmed due to cancellation of reserved tickets.
WL: Wait List
Wait iist means that the ticket will get confirmed if some tickets get cancelled. The traveller is not allowed to board the train with wait list ticket even though most of the people still board the trains in the hope that if some confirmed ticket traveller don't turn up, they can get the seat through Ticket Checker.
RLWL:Remote Location Wait List
PQWL: Pooled Quota Wait List
REGRET/WL1: No More Booking Permitted
Once the waiting list gets to large numbers, the booking for tickets for that train on that day gets stopped and the REGRET/WL1 message is shown.