Terrapins are one of several species of small turtle (order Testudines) living in fresh or brackish water. Terrapins do not form a taxonomic unit and may not be closely related. Many belong to the families Geoemydidae and Emydidae.
The name "terrapin" is derived from torope, a word in an Algonquian language that referred to the species Malaclemys terrapin (the Diamondback terrapin). It appears that the term became part of common usage during the colonial era of North America and was carried back to Great Britain. Since then, it has been used in common names for testudines in the English language.
