A square board with a handle used for holding and carrying masonry mortar.(noun)
An academic cap topped by a flat square.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "mortarboard" in a sentence
"I'm looking forward to reading the "mortarboard" version after the Copenhagen conference."
"Franz Mayer insisted on a three-month curing time for the "mortarboard," which accounts for the long lag time between demolition and installation."
"And they put a mortarboard on her chair in the front row."