Never knew the use of anonym as such either; pseudonym has this little ring of falseness to it. A false name , so I felt like looking it up:

Bartleby.com
Syllabication: pseu-do
Adjective: False or counterfeit
Etymology : from pseudo

Pseudo ,noun: a person who makes deceitful pretenses;
adjective: (often used in combination) not genuine but having the appearance of
(Example: "A pseudo esthete")

Etymology:
pseudo: comb. form meaning "false, feigned, erroneous," from Gk. pseudo-, comb. form of pseudes "false," or pseudos "falsehood," both from pseudein "to deceive." The prefix has been used as a stand-alone word for "false person, pretender" since c.1380.