noun
prizewinner; lottery winner
Refers to a person who has won a prize, typically in a lottery, sweepstakes, or contest.
宝くじの当せん者が発表された。
The lottery winners were announced.
当せん者には賞品が送られます。
Prizes will be sent to the winners.
当選者 is more common for election winners, while 当せん者 is typically used for prize or lottery winners.
Compound of 当せん (winning a prize/lottery) + 者 (person). The middle character せん is a simplified representation of 籤 (lottery).