Definition of measles
1 a
: an acute contagious disease that is caused by a morbillivirus (species Measles virus) and is marked especially by an eruption of distinct red circular spots — called also
rubeola
b
: any of various eruptive diseases (such as German measles)
2
[Middle English mesel infested with tapeworms, literally, leprous, from Anglo-French, from Medieval Latin misellus leper, from Latin, wretch, from misellus, diminutive of miser miserable]
: infestation with or disease caused by larval tapeworms in the muscles and tissues 
