Let
 An invalid point which has to be replayed.
 Occurs most frequently when a serve touches
 the net but still lands in the correct service
 court.

 Line judge
 Line judges have the task of deciding whether
 a ball has landed in the court or outside. Their
 decisions can only be overruled by the umpire.

 Lob
 A lob is a ball hit in a high arc, usually over the
 opponent's head. For the most part it is played
 when the opponent is standing at the net.

 Longline
 A stroke played straight down the court, either
 along or adjacent to one of the sidelines.

 Love
 Zero in tennis language, e.g. love-thirty = 0-30.

 Lucky Loser/Playback
 In some knockout tournaments, one defeat
 does not automatically result in elimination.
 Beaten players have the chance to play
 against other such losers, with the winners
 being awarded places in later rounds. These
 players are known as "lucky losers."