Middle English; earliest use found in St. Thomas Becket. From soul + mass. Compare Middle Dutch sielmisse, zielmisse (Dutch zielmis), Middle Low German sēlmisse, sēlemisse, Middle High German sēlmësse (German Seelenmesse), Old Icelandic sálumessa, Old Swedish siälamässa (Swedish själamässa), Old Danish, Danish sjaelemesse.