Wicket
Wicket was a cricketing term with diverse definition.
Primarily, it was the object of central focus in the sport of cricket. Comprised of three stumps and two bails, it was the thing that batsmen were guarding and the thing bowlers were attacking. Batsmen were dismissed if the bowler made the bails fall off the stumps by sending his ball past the batsman into the wicket. This act often drew loud reaction by on-lookers and players alike. From inside the comfort of the Black Horse Inn in the village of Cherhill, the Brigadier, for instance, could hear the spectators react when wickets fell. (PROSE: The Shadows of Avalon)
A wicket was also a synonym for the cricket pitch itself, as Lord Charles Cranleigh made clear when he called the wicket on the Cranleigh Hall ground "very green". (TV: Black Orchid) The Fifth Doctor himself also clearly indicated the meaning when on the Eye of Orion with Tegan and Turlough. He suggested that they could all play a few impromptu overs if only they could find a place to mark out the pitch. He found the particular ground he was marking out to be a "bit of a bumpy wicket" as he was pacing out the area to place the stumps. (PROSE: The Eight Doctors)
Behind the scenes
Another definition for the word not adequately explained in DWU fiction is that of the un-dismissed batsman. When, for instance, summary statistics are given about a cricket match, and a side is said to have "won by three wickets", that means that of their ten total batsmen, three were still standing by the time the number of runs needed to win had been scored.
