Original sentence: A more prosaic (but probably more correct) translation, is via conjugation of nemo (to consider): "Concerning the dead".Another etymology that has been suggested here is "Knowledge of the Dead", from Greek 'Nekrós', corpse, dead, and 'Gnomein', to know (on the apparent assumption that the G could be lost); the person so suggesting thinks this  "seems to fit better with the subject treated in the book"
Edited sentence: A more prosaic (but probably more correct) translation, is via a declination of nemo (to consider): "Concerning the dead".Another interpretation that can be made of the origin of the name is "Knowledge of the Dead", from Greek 'Nekrós', corpse, dead, and 'Gnomein', to know, what seems to fit better with the subject treated in the book