What is the origin of the word "poop"?
According to Eric Partridge in his excellent book of word origins (Origins: A Short Etymological Dictionary of Modern English), "poop" comes from the Middle English word poupen or popen, and it originally meant "fart." The word was based on the sound of a fart. According to Robert Chapman, author of American Slang, "poop" came into use with its current meaning around 1900.