The term comes from the verb oír, "to hear," referring to the judge's obligation to listen to the parts of a judicial process, particularly during the phase of pleas.
The oidor de casados was a special type of judge that arose to deal with the de facto separation of many married couples during the colonization of the New World and the fact that, after leaving Spain, many married men abandoned their lawful wives and entered into informal relationships with either native or European women.
In order to deal with this, the crown felt it was necessary to create this office to legally compel the reconciliation of the married couple.
Over time, the powers of the oidor de casados evolved to cover all types of lawsuits between a married couple.
Due to the general use of the word oidor, the term was also applied to the clerics who served as judges in ecclesiastical courts, although they had nothing to do with the audiencias.