Definify.com
Webster 1913 Edition
Michaelmas
Mich′ael-mas
,Noun.
[
Michael
+ mass
religious service; OE. Mighelmesse
.] The feast of the archangel Michael, a church festival, celebrated on the 29th of September. Hence, colloquially, autumn.
Webster 1828 Edition
Michaelmas
MICH'AELMAS
,Noun.
1.
In colloquial language, autumn.