Game feel (sometimes referred to as "game juice") is the intangible, tactile sensation experienced when interacting with video games
“Game feel” (a.k.a. “juice”) is the “aesthetic sensation of control” (Steve Swink, Game Feel) you have when playing a game.
Juice is what makes a game satisfying to play. It makes a jump feel like a mechanical robotic action, or a powerful leap.
Juice can be applied to regular design too. It makes something feel satisfying. It's not limited to big actions either, rote actions can benefit from juice.