Mortarboard (Square academic cap)

Mortarboard (Square academic cap)

The square academic cap, graduate cap, cap, or mortarboard (because of its similarity in appearance to the hawk used by bricklayers to hold mortar) or Oxford cap, is an item of academic head dress consisting of a horizontal square board fixed upon a skull-cap, with a tassel attached to the centre. In the UK and the US, it is commonly referred to informally in conjunction with an academic gown worn as a cap and gown. It is also sometimes termed a square, trencher, or corner-cap. The adjective academical is also used.

The cap, together with the gown and (sometimes) a hood, now form the customary uniform of a university graduate, in many parts of the world, following a British model.

The mortarboard is generally believed by unknown scholars to have developed from the biretta, a similar-looking hat worn by Roman Catholic clergy. The biretta itself may have been a development of the Roman pileus quadratus. The Italian biretta is a word derived from berretto, which is derived itself from the Latin birrus and the Greek pyrros, both meaning "red." The cone-shaped red (seldom in black) biretta, related to the ancient Etruscan tutulus and the Roman

 pileus, was used in the fourteenth and fifteenth centuries to identify humanists, students, artists, and learned and blooming youth in general. 

Ferstly it was  reserved for holders only of master's degrees (the highest qualification in mediæval academia) but was later adopted by bachelors and undergraduates. In the 16th and 17th centuries corner-cap ("catercap" in the Marprelate tracts) was the term used (OED).