The OED says:

Quote:
As noun < Hellenistic Greek ὀνομαστικόν onomasticon n. As adjective < ancient Greek ὀνομαστικός of or belonging to naming < ὀνομαστός named ( < ὀνομάζειν to name ( < ὄνομα name: see onomato- comb. form) + -τός , suffix forming verbal adjectives) + -ικός -ic suffix.


onoma "name" is verbed to onomazein "to name"
onomazein "to name" plus the suffix -tos gives onomastos "named" (the z turns into s?)
onomastos plus the suffix -ikos gives onomastikos "of or belonging to naming"
the noun form of onomastikos is onomastikon

Last edited by goofy; 10/06/2011 6:25 PM.