A book written by hand.
The word manuscript, literally 'handwritten', has come to be used to describe a book written by hand. It is abbreviated as ms. (singular) and mss. (plural).
[Local usage varies, so the abbreviation may also appear as Ms., MS., or even without the period. Manuscripts should generally be cited using the form established by the repository that owns the item.]
Michelle Brown, Understanding Illuminated Manuscripts (Malibu, CA: J. Paul Getty Museum in association with the British Library, c1994).