early 15c., "bodily fluid;" c. 1600 in specific sense of "mass of semi-liquid food in the stomach," from Latin chymus, from Greek khymos, nearly identical to khylos (see chyle) and meaning essentially the same thing. Differentiated by Galen, who used khymos for "juice in its natural or raw state," and khylos for "juice produced by digestion," hence the modern distinction.