CHUKKER: There are six chukkers, or periods, in a full-length outdoor game, four in arena polo. Each lasts seven minutes. There is no overtime at the end of the last chukker unless the score is tied, in which case a seventh period will be played.
HANDICAP: Handicaps in polo range from -2 to 10 “goals,” with 10 being the best. A player who is playing above his handicap level (i.e. 3 playing as a 5) is known as a ringer and is a very valuable but short-lived commodity, as handicaps are assessed and revised twice a year.
LINE OF THE BALL: This is the concept governing traffic on the filed: The ball creates an imaginary line as it travels, and the player or players established in this line have the right of way.
OFF SIDE: The right-hand side of a horse.
RIDE-OFF: This is when one player makes contact with another and attempts to push him off the line of the ball to prevent his hitting the ball.
SIDEBOARDS: These 9- to 11-inch boards along the sides of the field are optional; they contain the ball to an extent. A player can cross the boards and remain in play, but if the ball hops over them, it’s out of bounds.
THROW-IN: A chukker begins (and sometimes play resumes) with the umpire bowling the ball between the two teams.
UMPIRES: Two mounted umpires control the game, enforce the rules and guard the safety of players and ponies.
Source: International Polo Club Magazine 2013 issue article by Alex Webbe