allonym

[al-uh-nim] /ˈæl ə nɪm/
noun
1.
the name of another person taken by an author as a pen name.
Compare pseudonym.
2.
a work published under a name that is not that of the author.
Origin
1865-70; all- + -onym; cf. pseudonym
Related forms
allonymous
[uh-lon-uh-muh s] /əˈlɒn ə məs/ (Show IPA),
adjective
allonymously, adverb
British Dictionary definitions for allonym

allonym

/ˈælənɪm/
noun
1.
a name, often one of historical significance or that of another person, assumed by a person, esp an author