Crossword Dictionary
lob
lob - n 
an easy return of a tennis ball in a high arc 
the act of propelling something (as a ball or shell etc.) in a high arc 
A lob in tennis involves hitting the ball high and deep into the opponent's court. It can be used as an offensive or defensive weapon.
A lob is usually hit when an opponent is standing near the net, waiting to volley. The ball should pass over the opponent and into the open court behind. A good offensive lob cannot be reached by the opponent, yet it is low enough and has enough pace and spin so that the opponent can not run back and chase it down. It can win the point outright, although with some risks involved. Topspin greatly enhances the effectiveness of an offensive lob but also makes the stroke more difficult. When executing the lob, players usually hit the ball at an angle between 0 degrees (flat) and 45 degrees (diagonal). Some players, such as Andre Agassi, Michael Chang, Andy Murray and Lleyton Hewitt, have developed good offensive lobs.