natron (n.)

"native carbonate of sodium," 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.