Money generally.
A quarter of a pound or one crown, historically minted as a coin of approximately the same size and composition as a then-contemporary dollar coin of the United States, and worth slightly more.
Official designation for currency in some parts of the world, including Canada, the United States, Australia, New Zealand, Hong Kong, and elsewhere. Its symbol is $.
Imported from the United States, and paid for in U.S. dollars. (Note: distinguish "dollar wheat", North American farmers' slogan, meaning a market price of one dollar per bushel.)
A unit of reactivity equal to the interval between delayed criticality and prompt criticality.
Money in general.
In the United Kingdom and Ireland, a unit of currency worth ¹⁄₂₄₀ of a pound sterling or Irish pound before decimalisation, or a copper coin worth this amount. Abbreviation: d.
In the United Kingdom, a unit of currency worth ¹⁄₁₀₀ of a pound sterling, or a copper coin worth this amount. Abbreviation: p.
A unit of nail size, said to be either the cost per 100 nails, or the number of nails per penny. Abbreviation: d.
In various countries, a small-denomination copper or brass coin.
In the US and (formerly) Canada, a one-cent coin, worth ¹⁄₁₀₀ of a dollar. Abbreviation: ¢.
In Ireland, a coin worth ¹⁄₁₀₀ of an Irish pound before the introduction of the euro. Abbreviation: p.
To circumvent the tripping of an electrical circuit breaker by the dangerous practice of inserting a coin in place of a fuse in a fuse socket.
During a meal or as part of a drinking game, to drop a penny in a person's drink such that they must finish it (or some such variation thereof); commonly associated with crewdates at Oxford and swaps at Cambridge.
To jam a door shut by inserting pennies between the doorframe and the door.