What gets a water polo player thrown out of the game for good?

• Misconduct: "the use of unacceptable language, aggressive play, refusing obedience to or showing disrespect for a referee or official, or behaviour against the spirit of the Rules and likely to bring the game into disrepute".
• The penalty for misconduct: exclusion from the rest of the game. The player must leave the competition area. A substitute enters at the earliest normal re-entry moment.
• Violent action: kicking or striking an opponent or an official, "or attempting to kick or strike with malicious intent". It can happen during play, at a stoppage, in a timeout, after a goal or in an interval.
• The penalty for a violent action during play: exclusion from the rest of the game, a penalty throw to the other team, and no substitute until four minutes of actual play have passed.
• At a stoppage: the same, without the penalty throw.
• Both teams at once: both players are out for the game. Each team takes a penalty throw, the team that had the ball going first, and that team then restarts with a free throw.
• Leaving the water without permission: counted as misconduct.
• After the game: the tournament's management committee decides within 24 hours whether the player misses further games.

The glossary has misconduct and violent action.

A kick or a punch under water can injure and is easy to hide. The rules answer with the three heaviest penalties they have at once: the player, a penalty throw and four minutes short. Misconduct is kept apart because bad language should not cost a team as much as a punch.