{ ||Di*ach"y*lon (?), ||Di*ach"y*lum (?), } n. [NL. diachylum, fr. Gr. &?; very juicy; dia` thoroughly + &?; juice.] (Med. & Chem.) A plaster originally composed of the juices of several plants (whence its name), but now made of an oxide of lead and oil, and consisting essentially of glycerin mixed with lead salts of the fat acids.