1680s, from French natron (1660s), which is said to be directly from Arabic natrun, itself from Greek nitron, itself possibly of Eastern origin (see nitre). Medieval Latin and Paracelsus (16c.) had a form anatron, from Arabic with the article assimilated (an-natron). It is the source of the chemical symbol Na for sodium and the word-forming element natro-, used in the names of minerals to indicate the presence of sodium.