Of names

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Onomastic \On`o*mas"tic\, a. [Gr. ?, from ? to name, 'o`noma name.] (Law) Applied to a signature when the body of the instrument is in another's handwriting. --Burrill.

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1716, from French onomastique (17c.), from Greek onomastikos "of or belonging to naming," from onomastos "named," verbal adjective of onomazein "to name," from onoma "name" (see name ).

WordNet Word definitions in WordNet
adj. of or related to onomastics; "he published a collection of his onomastic essays"

Wiktionary Word definitions in Wiktionary
a. 1 of, or relating to a personal or place name 2 of, or relating to onomastics