During World War II, Germany fielded many aircraft and rockets whose fuels, and oxidizers, were designated (letter)-Stoff. In German, Stoff means roughly the same thing as English "stuff", both of which derive from the Old French word estoffe (meaning cloth or material). Stoff has as broad a range of meanings, ranging from "chemical substance" to "cloth", depending on the context. The common elements (hydrogen, oxygen, carbon and nitrogen) are named respectively Wasserstoff, Sauerstoff, Kohlenstoff and Stickstoff in German. Stoff was used in chemical code names in both World War I and World War II. Some code names were reused between the wars and had different meanings at different times; for example, T-Stoff meant a rocket propellant in World War II, but a tear gas (xylyl bromide) in Worl