a bump is where you hit the volleyball with your arms by making a fist with one hand and wrapping your other hand around the fist tightly. then you swing your arms up (no higher than your shoulders) so the ball hits and bounces off. the ball should hit about 2-3 inches above your wrist. if you bump off a serve, you typically dont need to swing your arms, it should just bounce off.
The volleyball bump is "la manchette" (feminine noun, from manche - sleeve) in French.
A bump is an under hand pass using only the flat platform you make with your forearms while playing volleyball.
A hic is a one armed bump.
The bump is called the forearm pass.