As per Oxford Dictionary document means:

"A deed, writing, inscription that furnishes evidence";

Section 3 of Evidence Act, defines document to mean any matter, expressed or described, upon any substance by means of letters, figures, or marks or by more than one of these means intended to be used or which may be used for the purpose of recording that matter

Section 3(18) of the General Clauses Act and Section 29 of the Indian Penal Code also defines what is document??