protein (n.)

1844, from French protéine, coined 1838 by Dutch chemist Gerhard Johan Mulder (1802-1880), perhaps on suggestion of Berzelius, from Greek prōteios "the first quality," from prōtos "first" (see proto-) + -ine (2).

Originally a theoretical substance thought to be a constituent of food essential to life, further studies of the substances he was working with overthrew this, but the words protein and proteid continued to be used in international work on the matter and also for other organic compounds; the modern use as a general name for a class of bodies arose in German. The confusion became so great a committee was set up in 1907 to sort out the nomenclature, which it did, giving protein its modern meaning ("class of organic compounds forming an important part of all living organisms") and banishing proteid.