‖n. pl. [ L. ] 1. Plural of erratum. See Erratum. [ 1913 Webster ]
2. A list of errors together with the corrections for the errors, added as a separate page of a text prior to publication, or as a separate sheet inserted into a printed text; as, the errata was added after the printing was finished.. [ PJC ]
Although originally a plural word, the use of errata as a singular word in second sense has become common. [ PJC ]