The
square academic cap,
graduate cap,
cap,
mortarboard (because of its similarity in appearance to the
hawk used by
bricklayers 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 worn as a cap and gown. It is also sometimes termed a
square,
trencher, or
corner-cap. The adjective
academical is also used.