DISMAL, an adjective meaning dreary, gloomy, and so a name given to stretches of swampy land on the east coast of the United States, as the Dismal Swamp in Virginia and North Carolina. The derivation has been much discussed. In the early examples of the use the word is a substantive, especially in the expression "in the dismal," i.e. in the dismal time or days. Later it became adjectival, especially in combination with "days." It has been connected with "decimal," med. Latin decimalis, belonging to a tithe or tenth, and thus the "dismal days" are the unpleasant days connected with the extortion and oppression of exacting payment of tithes. According to the New English Dictionary, quoting Professor W. W. Skeat, "dismal" is derived, through an Anglo-Fr. dis mal, from the Lat. dies mali, evil or unpropitious days. This Anglo-French expression, explained as les mal jours, is found in a MS. of Rauf de Linham's Art de Kalender, 1256. These days of evil omen were known as Dies Aegyptiaci (Du Cange, Glossarium, s.v.) or Egyptian days, either as having been instituted by Egyptian astrologers or with reference to the "ten plagues"; so Chaucer, "I trowe hit was in the dismal, That were the ten woundes of Egipte" (Book of the Duchesse, 1206). There were two such days in each month
See Skeat, Trans. Philol. Soc. (1888), p. 2, and note on the line in the "Book of the Duchesse," The Complete Works of Geoffrey Chaucer, vol. i. (1894).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)