This is the 15840th most frequent Russian word.
проигравших
"Проигравших" means "those who lost" or "losers" in English.
The word 'проигравших' is used as a plural noun to describe the individuals who lost in a competition.
В соревновании было несколько выигравших и несколько проигравших.
In the competition, there were several winners and several losers.
Here, 'проигравших' functions as an adjective-like participle describing people who lost.
Учитель объяснил тактику проигравших в игре.
The teacher explained the strategy of the losers in the game.
Again, 'проигравших' is used as a noun describing the group of individuals who didn't succeed.