Before the 16th century, "curtal" was a verb that meant "to dock (or cut short) an animal's tail," and a noun that meant "an animal with a docked tail." "Curtal" became "curtail" through a process called "folk etymology," in which words are transformed so that they appear to be related to better-known words. Since the meaning of "curtal" made people think of animals' tails, they substituted the word "tail" for "-tal," and "curtal" became "curtail." Eventually "curtail" came to be used for anything that was made less by being cut off or as if by being cut off.