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.
In previous centuries, academic dress was the everyday clothing of all students and faculty. 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. In other countries, especially the United States, mortarboards are only worn during the commencement ceremony itself.
