Brief descriptions of most common fouls provided below. Click here for diagrams of referee signals.
Occurs when a player¹s stick viciously contacts an opponent in any area other than the stick or gloved hand on the stick.
Occurs when a player obstructs his opponent at or below the waist with the crosse, hands, arms, feet or legs.
Occurs when a player uses the handle of his crosse between his hands to make contact with an opponent.
Occurs when any player or coach commits an act which is considered unsportsmanlike by an official, including taunting, arguing, or obscene language or gestures.
Occurs when a player strikes an opponent with his stick or body using excessive or violent force.
Illegal Body Checking:
Occurs when any of the following actions takes place:
A. body checking an opponent who is not in possession of the ball or within five yards of a loose ball;
B. avoidable body check of an opponent after he has passed or shot the ball;
C. body checking an opponent from the rear or at or below the waist;
D. body checking an opponent above the shoulders. A body check must be below the shoulders and above the waist, and both hands of the player applying the body check must remain contact with his crosse.
Occurs when a player uses a crosse that does not conform to required specifications. A crosse may be found illegal if the pocket is too deep or if any other part of the crosse was altered to gain an advantage.
Occurs when a player uses gloves that do not conform to required specifications. A glove will be found illegal if the fingers and palms are cut out of the gloves, or if the glove has been altered in a way that compromises its protective features.
Occurs when an offensive player deliberately, through his own momentum, enters the opponent¹s goalcrease or a defensive player, including the goalkeeper, with the ball in his possession, enters from the surrounding playing field into his own goal-crease.
Illegally impedes the movement of an opponent with the ball.
Illegal Offensive Screening:
Occurs when an offensive player, through moving contact of his body or equipment, blocks a defensive player from the man he is playing, or impedes his normal movements of playing defense.
Occurs when a player interferes in any manner with the free movement of an opponent, except when that opponent has possession of the ball, the ball is in flight and within five yards of the player, or both players are within five yards of a loose ball.
Occurs when a team does not have at least four players on its defensive side of the midfield line or at least three players on its offensive side of the midfield line.
Occurs when a player thrusts or shoves a player from behind.
Occurs when a team intentionally holds the ball, without conducting normal offensive play, with the intent of running time off the clock.
Occurs when a player in possession of the ball uses his free hand or arm to hold, push or control the direction of an opponent¹s stick check.
Withholding The Ball From Play:
Occurs when a player clamps a loose ball against the ground more than momentarily or clamps the ball against his body to prevent it from being dislodged.
Above info from US Lacrosse.