from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A natural vitreous gray or white mineral, Na2CO3·NaHCO3·2H2O, used as a source of sodium compounds.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A saline evaporite, consisting of mixture of sodium carbonate and sodium bicarbonate, Na3HCO3CO3·2H2O.
from the GNU version of the Collaborative International Dictionary of English
- n. A native double salt, consisting of a combination of neutral and acid sodium carbonate, Na2CO3.2HNaCO3.2H2O, occurring as a white crystalline fibrous deposit from certain soda brine springs and lakes; -- called also urao, and by the ancients nitrum.
from The Century Dictionary and Cyclopedia
- n. The native soda of Egypt, a hydrous carbonate of sodium, Na2CO3.HNaCO3 + 2H2O.
Swedish, probably from Arabic dialectal ṭrōn, variant of Arabic naṭrūn, natron; see natron.(American Heritage® Dictionary of the English Language, Fourth Edition)
From the Swedish trona or from the Spanish trona, both derived from the Arabic اطرون (atrūn), which derives from the Arabic نطرون (natrūn); from the Ancient Greek νίτρον (nitron), from the Ancient Egyptian ntry. (Wiktionary)