Suppression occurs when a player is being shot at, even if they are not being hit. When suppressed, a player's vision will become shaky and eventually go grey, and they will be more vulnerable to being killed as their accuracy decreases.
Suppression is based on volume of fire; therefore, a large amount of automatic weapons firing at the same target will suppress it much more than semi-automatic weapons.
Suppression Assist Edit
If a player is suppressing an enemy and they are killed by a teammate, they will get a Kill Assist, though it is only worth 15 points and is known as a Suppression Assist. This generally happens if the player who got the assist did not hit the player they are suppressing enough times to get a regular Kill Assist.