Bullet game
It's one where the time control is less than 3 minutes at the start. The most common options are
1|0 - 1 minute at the start, no increment
2|1 - 2 minutes at the start, plus 1 second for every move played
At the moment, Chess.com also classes games where you get less than 1 minute at the start as bullet games, but I think they might be changing that and putting those into a separate "hyperbullet" category.