A secular festival; a holiday. Note: Holiday is the preferable and prevailing spelling in the second sense. The spelling holy day or holyday in often used in the first sense.
... camp, behold us throng, Flags stream, and bugles play— Woman and child with choral song, And men, with dance and wine, prolong The warrior's holyday. ... — Blackwood's Edinburgh Magazine, Vol. 53, No. 331, May, 1843 • Various