Dictionary.com
definitions

sphenoid bone

noun
  1. the large butterfly-shaped compound bone at the base of the skull, containing a protective depression for the pituitary gland
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
sphenoid bone in Medicine

sphenoid bone

n.
  1. A compound bone with winglike processes, situated at the base of the skull.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.