mortarboard

n. 1. A small square board with a handle beneath, for holding mortar; a hawk; used by masons to hold or carry mortar. [ 1913 Webster + WordNet 1.5 ]

2. An academic cap topped by broad, projecting, stiff and flat square top, with a tassel attached to the top and hanging down. It was once worn by students in some colleges, but is now worn usually only at graduation ceremonies. [ 1913 Webster + WordNet 1.5 ]