Worm
a plot of either the cumulative runs scored, or the progressive run rate achieved by a team (the y-axis) against the over number (x-axis) in limited-overs cricket. Wrist spin
a form of spin bowling in which the ball is made to rotate by the position and/or movement of the bowlers wrist (contrast with finger spin). For a right-handed bowler this produces leg spin, whereas the same technique by a left-handed bowler produces left arm unorthodox spin. Wrong foot
when the bowling foot is the front foot the delivery is said to be bowled off the wrong foot. Such a bowler is said to bowl off the wrong foot. Wrong footed
when the batsman is initially moving either back or forward to a delivery and then has to suddenly change which foot they use (back or front), they are said to have been wrong-footed. Usually applies to spin bowling. Wrong un
another name for a googly; most common in Australia. Y
Yes
batsmans call for a run. See No, Push, Two, Wait. (The) Yips
The yips are occasionally experienced by bowlers suffering from a loss of confidence. A psychological condition whereby the bowler is unable to sufficiently relax when delivering the ball – often holding the ball too long before release, losing flight, turn and accuracy in the process. Bowlers have been known to suffer from the yips for as little as a few overs, up to the course of an entire season or more. Yorker
a (usually fast) delivery that is pitched very close to the batsman.
The intent is for it to pitch exactly underneath their bat or on their toes, in the block hole. A perfectly pitched fast yorker is very difficult for a batsman to play; however a poorly delivered yorker can turn into a half-volley (too short) or a full toss (too full). Z
Zooter or Zoota 
a variation of the flipper bowled by a leg-break bowler. Typically, Zoots along the ground without much bounce. This ball is possibly a myth made up by Shane Warne to create confusion amongst opposition sides. Notes
References

Printed sources:

Eastaway, Rob (1992). What is a Googly? (first ed.). Robson Books. Booth, Lawrence Arm-ball to Zooter. A sideways look at the language of cricket, pub. 2006, Penguin. ISBN 0-14-051581-X
Rundell, Michael The Wisden Dictionary of Cricket, Third edition, A & C Black, London, 2006. ISBN 0-7136-7915-8
Piesse, Ken the Extraordinary Book of Australian Cricket, Penguin, Australia.Websites:

A glossary of cricket terms from CricInfo
Glossary of cricket terms from the England Cricket Board
Cricket Academy – Glossary from BBC News
"fielding positions" from CricInfo