A cryptid is a creature (or occasionally, a plant) whose existence is claimed, but is regarded by scientific consensus as impossible or extremely unlikely. Famous cryptids include Scotland's Loch Ness Monster, the Yeti of the Himalayas, and North America's Bigfoot (aka Sasquatch).
The term cryptid was originally coined by John E. Wall in a 1983 letter to the International Society of Cryptozoology newsletter. Before this time, the word was used exclusively to refer to members of the Cryptinae subfamily of wasps, and there was no well-established term to describe legendary creatures of dubious scientific standing.