許さんは許さないという意味ですか？
I came across this word 許さん on the internet forum and was wondering if it is a short-form of 許さない. This remains me of another word which I commonly see, わからん. I suppose they are the same. Is this formal or just for colloquial? If it is the former, then what is this form of verb call? Also, what is the rule to change into this form?

Question

Answer

V (nai-form)+ない can be turned into V(nai-form) + ん, partly for the convenience of the pronunciation. 
 ‘V(nai-form) + ん’ sounds quite rough(not formal), and is mainly used be men. Ladies may use it,  sort of jokingly. 
you might save it until you really get sure of the connotation.

Answer

許さんは許さないという意味です。
Very good!(^o^)/

Answer

許さん is colloquial & impolite word.(*o*)
わからん is same.
I never say 許さん&わからん(^o^)

Answer

許さん is a colloquial & no-polite word.
I never say that.(maybe^^)
I think don't use that!