Unlike its meanings, there's nothing terribly sticky about the origin and use of "mucilaginous." Like thousands of other words in the English language, "mucilaginous" (and the noun "mucilage") oozed out of Latin during the 15th century. "Mucilage" is from Late Latin's word for "mucus," mucilago, and is used for the gelatinous substance found in various plants, such as legumes or seaweeds. "Mucilaginous" stuck as the noun's adjective form and is used by scientists and foodies alike for sticky or mucous things.