fast dayn.

a. A day appointed for or marked by abstinence from all or some kinds of food or drink as an act of religious devotion or discipline. Cf. fasting day n. Rare before 17th cent.

b. A publicly proclaimed day of fasting, humility, and prayer, typically intended to secure divine aid or favour for a particular purpose, in a time of disease, adversity, etc.; (later U.S. regional (New England)) an annual public holiday, originally instituted as such a day of fasting. Now historical.Such days were proclaimed in England from at least the early 17th cent., and later also in the New England colonies throughout from the 1700s to the early 19th cent. By the nineteenth cent., the celebration of an annual fast day had become traditional in some New England states, and, as work was traditionally prohibited on such days, they increasingly evolved into ordinary public holidays, and in the late 19th and 20th centuries were replaced with named holidays.

c. In Scottish Presbyterian churches: a day on which a congregation undertakes spiritual preparation before a Communion Sunday, now typically marked by attendance of church services and the confession of sins and personal repentance, but originally also involving fasting. Also more fully communion fast day, sacramental fast day.Typically the Thursday of the week preceding the yearly or twice-yearly Communion Sunday, when shops, schools, etc., in the local area would be closed; in early times often on the preceding Sunday. Since the end of the 19th century preparatory fast days have been observed by only a few communities, mainly in the Highlands and Islands.Quot. 1640 could alternatively be interpreted as showing use of sense 1b, but it seems more likely to belong here.