Pseudo- (from Greek: ψευδής, pseudés 'false') is a prefix used in a number of languages, often to mark something as a fake or insincere version.
[1] In English, the prefix is used on both nouns and adjectives.
It can be considered a privative prefix specifically denoting disproximation, i.e. that the resulting word refers to something that has moved away from the core meaning of the base that the prefix is added to.
[2] The meaning is the same in French and Greek, but in Greek it also attaches to other word classes such as verbs and adverbs.
[3]