I heard this word often and I'm pretty sure it means "correct! / right! / great!" but I cannot seem to find the word in dictionary and I don't even know how it is written. I try to find せっかい but have no match.
Could you help to confirm what word am I hearing?
You might be thinking of seikai, 正{せい}解{かい}
I hear it often used in game-shows indicating the contestant got the correct answer. It's hard to know for sure since you aren't providing a whole lot of context, but this would be my best guess.
Definition (according to jisho.org)
