in the Roman breviary, is applied to the several days of the week; thus Monday is the feria secunda, Tuesday the feria tertia; though these days are not working days, but holidays. The occasion of this was, that the first Christians were used to keep the Easter week holy, calling Sunday the prima feria, &c., whence the term feria was given to the days of every week. But besides these, they have extraordinary feriae, viz. the three last days of Passion week, the two following Easter day, and the second feriae of Rotation.