Twelfth man
Traditionally, the first substitute player who fields when a member of the fielding side is injured. In Test matches, twelve players are named to a team prior to the match, with the final reduction to eleven occurring immediately prior to play commencing on the first day. This gives the captain some flexibility in team selection, dependent on the conditions (e.g. a spin bowler may be named to the team, but omitted if the captain feels that the pitch is not suitable for spin bowling). Twenty20 (or T20) 
a form of limited overs cricket in which each team has one innings with a maximum length of twenty overs. Two
batsmans call for a probable two runs, requiring their partner to commit to a fast turn. See No, Push, Yes, Wait. U
Umpire
An official who enforces the laws and adjudicates play. One umpire stands behind the wicket at the non-strikers end, while a second (usually) stands at square leg, with the positions alternating for each over. The two on-field umpires use a system of arm signals to indicate decisions to the players and the scorer. Televised matches usually also have a third umpire to adjudicate on replays and the umpire decision review system. Umpire Decision Review System (UDRS)
(or Decision Review System, DRS)Official system to challenge certain decisions made by an umpire. The third umpire then reviews the decision using various technological aids, such as slow motion television replays, ball tracking, a snickometer etc.
It is done when the opposition plays a heavy off-side field and then bowl outside off. This shot was originally invented by Kevin Pietersen. It is also played by James Taylor and by New Zealand tailender Trent Boult
Flash
to wield the bat aggressively, often hitting good line and length deliveries indiscriminately. Flat pitch
a pitch which is advantageous to the batsmen and offers little or no help to the bowlers, due to predictable bounce. Also known as a "flat deck"

Flat hit
an aerial shot hit with significant power by the batsman which travels fast enough to make the ballistic trajectory of the ball appear flat

Flat throw
a ball thrown by the fielder which is almost parallel to the ground. Considered to be a hallmark of good fielding if the throw is also accurate because flat throws travel at a fast pace. Flat-track bully
a batsman high in the batting order who is very good only when the pitch is not giving the bowlers much help. Track is Australian slang for the pitch. When the track is said to be flat it is at its easiest for the batsman, but these are the only conditions under which some players can dominate. When conditions are tough, or when it really counts – they dont. Flick
a gentle movement of the wrist to move the bat, often associated with shots on the leg side. Flight
a delivery which is thrown up at a more arched trajectory by a spinner. Considered to be good bowling. Also loop.