pseudonym

As a noun pseudonym

is a fictitious name, often used by writers and movie stars.

As a verb nymshift is

to change one's pseudonym so as to appear to be posting messages as an unrelated user.

As nouns the difference between pseudonym and nymshifter

is that pseudonym is while nymshifter is (internet|often|derogatory) one who deceptively posts messages under several different pseudonyms.

As nouns the difference between pseudonym and nym

is that pseudonym is a fictitious name, often used by writers and movie stars while nym is a pseudonym used when posting messages.

As a noun pseudonym

is .

As an adverb pseudonymously is

under a pseudonym.

Pseudonym is an antonym of autonym.

As nouns the difference between pseudonym and autonym

is that pseudonym is while autonym is (taxonomy) an infraspecific name in which the species epithet is repeated.