a cent or penny
Cent: A decimal coin equal to one one-hundredth of a larger basic denomination, usually the lowest value coin issued by the issuing country. The word “cent” is derived from the Latin centum, meaning one hundred. The United States Cent is 1⁄100 of a Dollar; other countries that issue cents (or similar coins such as the centavo, centimo, or centime) always have a larger denomination equal to 100 cents. In fact, what the British now call their Penny might technically be considered a cent, since it is equal to 1⁄100 of a Pound.
Penny: A basic unit of coinage, with the name derived from the Roman denarius. Pennies have been minted in Great Britain since the eighth century, although similar coins such as the pfennig, denier, dinar, and dinero have been minted in many places throughout the world. Like the denarius, the British penny was originally a small silver coin, and only since 1797 has the denomination been minted in copper. The aggregate plural of the word “Penny” is “Pence”, and the accepted abbreviation for pence until very recently was a lower case ’d’, again from the Roman denarius.
Twelve British pence equaled a shilling, although this figure could vary for coins from elsewhere in the British Isles; a similar coin from the Isle of Man might pass at 14 to the shilling, for example. Similar denominations from elsewhere would pass based on their value or perceived value in comparison to whatever larger denomination coins were available.
In the US, the term “Penny” is slang for the cent. The United States has never issued a penny.
(Originally posted by Gary on USA Coin Group)
An interesting side note is that Biblical scholars agree that the coin Christ held up when He said, “Render unto Caesar that which is Ceasars, and that which is God’s unto God”, was a denarius bearing a portrait of Tiberius. Today, those coins are referred to as a “Tribute Penny”.
(Added by Tom aka coinguy)