Square academic cap

The square academic cap, graduate cap, cap, mortarboard (because of its similarity in appearance to the mortarboard used by brickmasons to hold mortar) or Oxford cap, is an item of academic 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, 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 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, a type of skullcap with superposed square and tump (meaning small mound). A reinvention of this type of cap is known as the Bishop Andrewes cap. 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. The shape and the colour conveyed meaning: Red was considered for a long time the royal power, whether because it was difficult to afford vestments of such solid and brilliant dye or because the high symbolic meaning of blood and life, thus the power over life and death.

It is not casual that the capo (captain) headwear is found with such frequency in Renaissance paintings as the highly famous one by Piero della Francesca of Federico da Montefeltro with his red cap. Campano wrote about these hats in his Life of Niccolò Fortebraccio, "he used to wear a red and high hat, the higher from the head the wider it became." Federico and Niccolò were Condottieri. The same cap is seen on Bartolomeo Colleoni, commander of the Venetian Armies in 1454, on the Duke Ludovico III Gonzaga and on John Hawkwood in his equestrian monument by Paolo Uccello. This cap as worn by the leading Italian nobles at the end of the fifteenth century became a symbol of their military and civil powers over Italian cities at a time when the whole of Europe was going to be deeply transformed by Italian influences.

...
Wikipedia