1) Lexicology 2) Of names 3) Of or related to onomastics 4) Pertaining to proper names 
of, like or pertaining to a name or signature
• (a.) Applied to a signature when the body of the instrument is in another`s handwriting.
Related to names. For instance, a character's name might contain an onomastic symbol--if that charac
On`o·mas'tic adjective [ Greek ..., from ... to name, ... name.] (Law) Applied to a signature when the body of the instrument is in another's handwriting. Burrill. 
onomastic 1. Of, like, or pertaining to a name or a signature.2. Pertaining to or consisting of names.
adjective of or related to onomastics; `he published a collection of his onomastic essays`