Can you spell Shabbat with an O

A reader asked if one can spell Shabbat with an "o" The word Shabbat is from the spelling in Hebrew שבת 

The vowels in Hebrew are as we spell Shabbat, with two vowels of "a", "a" sounding uh. 

If one wishes to greet someone in Yiddish, or with an Ashkenazi pronounciation then Shabbat is pronounced Shabbos, in which case there is an "o".

If you are now totally confused and wish to understand further, do visit us at Chessed Ve'Emet. We offer Torah learning online and in person and would be happy to answer your questions, including how to write or pronounce important words such as Shabbat.