Definition of "unbelievably"

unbelievably

adverb
comparative more unbelievably, superlative most unbelievably
1. (manner) In a manner that one does not or cannot believe.
  Quotations
  Almost unbelievably, some authors have formed the erroneous conception that ‘Hobson-Jobson’ is actually the double-barrelled surname of the dictionary’s editor.
  2018, James Lambert, “Setting the Record Straight: An In-depth Examination of Hobson-Jobson”, in International Journal of Lexicography, volume 31, number 4, page 488
2. (degree) To an extent not to be believed.
3. (evaluative) Contrary to expectations, amazingly.