Probable? Questionable? Doubtful? WTF?
Probable - The player had minor injuries, he practices during the week and very likely to play. 90-100% health condition.
Questionable - The player had some injuries, he had limited or no practice during the week and is unlikely to play. Day to Day/ Game-time decision. Do not expect them to perform at 100% even if they end up playing.
Doubtful - Very unlikely to start due to injuries. Do not start.