[1] : The Collaborative International Dictionary of English v.0.48

mortarboard \mortarboard\, mortar board \mortar board\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

[2] : WordNet (r) 2.0

mortarboard
     n 1: a square board with a handle underneath; used by masons to
          hold or carry mortar syn: hawk
     2: an academic cap with a flat square with a tassel on top
see also:
hawk 

Mortarboard >> M Words
Mortarboard, definition of term: Mortarboard
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