-onym

1.
a combining form of Greek origin, meaning “word,” “name”:
pseudonym.
Origin
ultimately < Greek -ōnymos having the kind of name specified, combining form representing ónyma, dialectal variant of ónoma name
British Dictionary definitions for -onym

-onym

combining form
1.
indicating a name or word: acronym, pseudonym
Word Origin
from Greek -onumon, from onuma, Doric variant of onoma name