A coin was a form of money.
One of the traditional ways to consult the I Ching was to toss coins. (TV: Warriors' Gate)
Around the late 20th century or early 21st century, Britain introduced a five pound coin. (TV: Battlefield)
The United Kingdom issued a commemorative pound coin celebrating the London 2012 Olympics, one of which ended up in a coin-operated vending machine in Manchester in 2008. (AUDIO: The Raincloud Man)
Searching through the pocket of the Ninth Doctor's leather jacket, Rose Tyler found a £10 coin which claimed to show the head of William V. (PROSE: Winner Takes All)
Since two co-existing kings ruled on Aldebaran III, coins issued there had two heads. (TV: The Pirate Planet) The Trions used coins with two heads. (PROSE: The Eight Doctors) Altairian dollar coins also had two heads. (AUDIO: Storm Warning)