What is "pseudocardinal"

Pseudocardinals were the cardinals created by the antipopes. Their state, like the state of the antipopes, is disputed. Many pseudocardinals were created during the controversy between the Holy See and the Holy Roman Empire during the Western Schism, and some of the cardinals switched their obedience. The legitimacy of the popes of the different obediences during the Western Schism was not a clear matter for their contemporaries. The terms antipope, pseudocardinal and anticardinal were not used at that time, but they are now used by some modern Roman Catholic historians.