1. 1. An acute, contagious viral disease, usually occurring in childhood and characterized by eruption of red spots on the skin, fever, and catarrhal symptoms. Also called rubeola.
   2. Black measles.
   3. Any of several other diseases, especially German measles, that cause similar but milder symptoms.
2. A disease of cattle and swine caused by tapeworm larvae.
3. A plant disease, usually caused by fungi, that produces minute spots on leaves and stems.

[Middle English maseles, mesels, pl. of masel, measles-spot, of Middle Low German origin.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.