The Collaborative International Dictionary of English v.0.48:

Notum \No"tum\, n.; pl. Nota. [NL., fr. Gr. nw^ton.] (Zool.)
   The back.
   [1913 Webster]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

NOTA
       None Of The Above (slang, Usenet, IRC)