cherubism

[chĕrə-bĭz′əm]
n.
  1. A hereditary disease marked by an enlargement of the jawbones in young children, producing a cherublike facial appearance.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.