text: The R symbol was introduced by 19th-century French chemist Charles Frédéric Gerhardt, who advocated its adoption on the grounds that it would be widely recognizable and intelligible given its correspondence in multiple European languages to the initial letter of "root" or "residue":  French  ("root") and  ("residue"), these terms respective English translations along with radical (itself derived from Latin  below), Latin  ("root") and  ("residue"), and German ' ("remnant" and, in the context of chemistry, both "residue" and "radical").