Pseudo is a prefix of Greek origin. It identifies something as superficially resembling the original subject; a pseudopod resembles a foot, and pseudorandom numbers simulate numbers generated by truly random events, but are in fact produced by an algorithm.
It is also used to mark something as false, fraudulent, or pretending to be something it is not in fact, as in pseudoscience or pseudophilosophy.
-eg. : pseudo-costate equations in control theory.
In Internet parlance, a pseudo is a computer program designed to simulate a human user. Pseudos analyze thousands of words of text of a forum member's postings, and generate randomly new posts from that data that are supposed to resemble a satire on the forum participant's style. Pseudos have been used in the past to post flames and fool forum participants into thinking one of their own has adopted an additional screenname and used it to flame. Comparisons to pseudos are invoked as a colossal insult to tell a user that his rantings resemble not his own posts, but a parody of his posts.