Do you have a reference for the use of 'n''k ? And do you know when the
Hebrew form first appeared?
Yigal Levin
It appears for the first time in the literature of the Masoretic movement
being derived from the Aramaic 'oraita, nevi'ei ukhtivei of B. Kid. 49a.
The original acronym was in the form 'n''k (Masoretic notes are usually
in Aramaic). Tanakh is the Hebrew reflection of the Masoretic term.