I had to look it up as well. I assumed it was a play on words about Microsoft, Nintendo, and Sony (the three big video game console players).
Monopoly is a single seller.
Monopsony is a single buyer.
There isn't a single seller so the proper ones are
Oligopoly - Market with few sellers
Oligopsony - Market with few buyers
"few" really meaning that they have pricing power as opposed to 3 companies.
I had to look it up as well. I assumed it was a play on words about Microsoft, Nintendo, and Sony (the three big video game console players).