From the Latin cucullus or cuculla, in contemporary English usage refers, in most cases, to the traditional monastic hood, which was adopted by the canons regular, friars, and religious of later institutions. In the English Benedictine Congregation, however, cowl historically referred to the large pleated choir robe that is worn by the monks during choral exercises. The other congregations of English-speaking monks called this garment by the Latin name cuculla. Both uses of the English word cowl are grounded in a long and complex history of monastic clothing and of the terminology by which it was designated. The cuculla referred to in the Rule of St. Benedict was probably a birrus cuculatus or hooded work-cloak of a kind worn outdoors especially by laborers in late imperial times. This hooded cloak continued to be used in a world of altered fashions and became the distinguishing characteristic of monastic dress. It took on a sacred significance comparable to that of the veil among the nuns; this significance was preserved by the Benedictines, among whom the cowl and the hood are given at the time of clothing. During the time of the monastic reforms of the 10th and 11th centuries, a large choir gown developed. This piece of clothing, which was often called a casula, was known also as a cuculla and was the prototype of the cowl or cuculla worn by choir monks. But the medieval use of the word cuculla was not uniform, and the meanings varied widely from place to place.
cowl / koul/ • n. a large loose hood, esp. one forming part of a monk's habit. ∎ a monk's hooded, sleeveless habit. ∎ a cloak with wide sleeves worn by members of Benedictine orders. ∎ the hood-shaped covering of a chimney or ventilation shaft. ∎ the part of a motor vehicle that supports the windshield and houses the dashboard. ∎ another term for cowling. DERIVATIVES: cowled adj.
the cowl does not make the monk appearance is no reliable guide to a person's true character (an element of deliberate deception is also sometimes implied). The saying is recorded from the late 14th century, but the 13th-century Ancrene Wisse has the related comment, ‘Her in is religiun, nawt i the wide hod ne i the blake cape.’