Zygomatic has the property, according to my dictionary, of appearing only in compounds: zygomatic arch, zygomatic bone, and zygomatic process. The definition of zygomatic bone in the American Heritage Dictionary is fun: “A small quadrangular bone in vertebrates on the side of the face below the eye; forming, in mammals, part of the orbit...” After some more jargon it finally admits “Also called ‘cheekbone.’”

Originally written June 1993.
Added here January 2012.