unit of force, 1904, named in honor of Sir Isaac Newton (1642-1727). Related: Newtonian.
also R.E.M., rem, unit for measuring ionizing radiation, 1947, acronym of roentgen equivalent man.
"unit of money or weight," late Old English marc, a unit of weight (chiefly for gold or silver) equal to about eight ounces, probably from Old Norse mörk "unit of weight," cognate with German Mark and probably ultimately a derivative of mark (n.1), perhaps in a sense of "imprinted weight or coin." It was a unit of account in England into 18c., perhaps originally introduced by the Danes, but never the name of a particular coin.
The word is found in all the Germanic and Romanic languages (compare Old Frisian merk, Dutch mark, Medieval Latin marca, French marc (11c.), Spanish and Italian marco); in English it was used from 18c. in reference to various continental coinages, especially the silver money of Germany first issued 1875.