A day other than the sabbath day. In the liturgy of the Catholic Church, a feria is a day of the week other than Sunday. In recent official liturgical texts in English, the term weekday is used instead of feria. If the feast of a saint falls on such a day, the liturgy actually celebrated may be that of the saint, not that of the feria. Accordingly, in actual liturgical practice a feria or ferial day is "a weekday on which no special ecclesiastical feast is to be celebrated".
Origin of the term
The Harvard Dictionary of Music explains the origin of the term feria as "the reverse of the original meaning of L. feria, i.e., festival day. The reversal came about by extending the use of the word from Saturday to the other days, Sunday being named feria prima, Monday feria secunda, Tuesday feria tertia, etc." Since in ecclesiastical Latin the names of Sunday and Saturday do not contain the word feria and are called respectively dominica and sabbatum, some use the term feria "to denote the days of the week with the exception of Sunday and Saturday", in spite of the official definition given above and the actual usage in official liturgical books. The Portuguese language uses the same terminology as ecclesiastical Latin for the days of the week, calling the days from Monday to Fridaysegunda-feira, terça-feira, etc., but calling Saturday sábado and Sunday domingo.
First-class ferias, outranking all feasts: Ash Wednesday and all the weekdays of Holy Week;
Second-class ferias, outranking local second-class feasts and, if impeded, requiring to be commemorated: ferias of Advent from 17 December to 23 December, and Ember Days of Advent, Lent and September;
Third-class ferias: ferias in Lent from Thursday after Ash Wednesday to Saturday before the Second Sunday of the Passion except Ember Days, and ferias in Advent up to 16 December except Ember Days ;
Fourth-class ferias: all other ferias.
Before 1960, the Roman Rite knew a simpler distinction between major and minor ferias. The major ferias were those of Advent and Lent, the Ember days, and the Monday of Rogation week. These had to be commemorated even on the highest feasts. All the others were minor ferias. In addition, the major ferias of Ash Wednesday and Holy Week were privileged: these liturgies were to be celebrated no matter what feast happened to occur on those days.