So I'm translating one of the readings in Thorgeirsson & Guthlaugsson and come across the word "brunnr."  Rather than flip through the Vocabulary section of the lesson, I grabbed Faulkes & Barnes "Glossary."  Couldn't find it there.  Went back to Th & G and found it glossed as "well."  Next I went online and looked it up in Zoega, and couldn't find it there, either.  So my question is, "What the heck?"  (or in modern English, "WTF?")  Did Th & G use a modern Icelandic word?  Do I not know how to look up words in the dictionary?  Is Faulkes & Barnes only limited to glossing the words used in their Reader?  Or what?
 
Thank you so much for your help!
   Alec MacLean