In the Torah the months have no names.They are
numbered (1st, 2nd etc.) except for Nissan which is called
In Tanach we find different names for some months.
ניסן = אביב, אייר = זיו, תשרי = ירח האתנים, מרחשון= בול
The months אלול,כסליו,טבת,שבט,אדר & ניסן appear in
Tanach (as is)
Chodesh Cheshvan in Tanach (Melochim 1:6:38 is referred
to as ירח בול month of Bul.
The Midrash (Tanchuma) writes that after the Mabul
it used to rain heavily for 40 days starting from Rosh
Chodesh Cheshvan. Shlomo Hamelech after completing
the Bais Hamikdash davened for the rain to stop.
Therefore the מ from מבול was removed and changed
to בול. (The month the Bais Hamikdash was completed)
The Pri Chadash writes if a Get was dated ירח בול it is
a kosher Get
The Rema (Hl. Gittin 126 :6) writes to spell the month
מרחשון (not חשון ) in a Get.
The Poskim (Pischei Teshuva- Get Poshut) rule if it was written חשון “
it is Kosher B’dieved.
Harav Hagaon R. Y.S. Elashiv zt"l ruled , If a Rosh Yeshiva,
Rov etc. was Mesader with a Kesubah spelled “ חשון “ ,
since B’dieved it is Kosher, you should not embarrass him
to correct his mistake.