Word Study
Onomastic
CIDE DICTIONARY
Onomastic, a. [Gr. , from to name, 'o`noma name.].
Applied to a signature when the body of the instrument is in another's handwriting. Burrill. [1913 Webster]
OXFORD DICTIONARY
Onomastic, adj. relating to names or nomenclature.
Etymology
Gk onomastikos f. onoma name
For further exploring for "Onomastic" in Webster Dictionary Online