The Collaborative International Dictionary of English v.0.48:

Pseudo- \Pseu"do-\ [Gr. pseydh`s lying, false, akin to psey`dein
   to belie; cf. psydro`s lying, psy`qos a lie.]
   A combining form or prefix signifying false, counterfeit,
   pretended, spurious; as, pseudo-apostle, a false apostle;
   pseudo-clergy, false or spurious clergy; pseudo-episcopacy,
   pseudo-form, pseudo-martyr, pseudo-philosopher. Also used
   adjectively.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pseudo
    adj 1: (often used in combination) not genuine but having the
           appearance of; "a pseudo esthete"; "pseudoclassic"
    n 1: a person who makes deceitful pretenses [syn: imposter,
         impostor, pretender, fake, faker, fraud, sham,
         shammer, pseudo, pseud, role player]

The Free On-line Dictionary of Computing (19 January 2023):

pseudo

    /soo'doh/ (Usenet) Pseudonym.

   1. An electronic-mail or Usenet persona adopted by a human
   for amusement value or as a means of avoiding negative
   repercussions of one's net.behaviour; a "nom de Usenet",
   often associated with forged postings designed to conceal
   message origins.  Perhaps the best-known and funniest hoax of
   this type is BIFF.

   2. Notionally, a flamage-generating AI program simulating
   a Usenet user.  Many flamers have been accused of actually
   being such entities, despite the fact that no AI program of
   the required sophistication yet exists.  However, in 1989
   there was a famous series of forged postings that used a
   phrase-frequency-based travesty generator to simulate the
   styles of several well-known flamers; it was based on large
   samples of their back postings (compare Dissociated Press).
   A significant number of people were fooled by the forgeries,
   and the debate over their authenticity was settled only when
   the perpetrator came forward to publicly admit the hoax.

   [Jargon File]

   (1995-03-13)


The Jargon File (version 4.4.7, 29 Dec 2003):

pseudo
 /soo'doh/, n.

    [Usenet: truncation of ‘pseudonym’]

    1. An electronic-mail or Usenet persona adopted by a human for amusement
    value or as a means of avoiding negative repercussions of one's
    net.behavior; a ‘nom de Usenet’, often associated with forged postings
    designed to conceal message origins. Perhaps the best-known and funniest
    hoax of this type is B1FF. See also tentacle.

    2. Notionally, a flamage-generating AI program simulating a Usenet user.
    Many flamers have been accused of actually being such entities, despite the
    fact that no AI program of the required sophistication yet exists. However,
    in 1989 there was a famous series of forged postings that used a
    phrase-frequency-based travesty generator to simulate the styles of several
    well-known flamers; it was based on large samples of their back postings
    (compare Dissociated Press). A significant number of people were fooled
    by the forgeries, and the debate over their authenticity was settled only
    when the perpetrator came forward to publicly admit the hoax.