Michaelmas

English

From Middle English Michelmasse, Myghelmesse; equivalent to Michael +‎ -mas.

Michaelmas (plural Michaelmases)

A Christian feast celebrated on the 29th of September in honour of the archangel Michael.
- 1750, W[illiam] Ellis, The Country Housewife's Family Companion: Or Profitable Directions for Whatever Relates to the Management and Good Œconomy of the Domestick Concerns of a Country Life, According to the Present Practice of the Country Gentleman's, the Yeoman's, the Farmer's, &c. Wives, in the Counties of Hertford, Bucks, and Other Parts of England: Shewing how Great Savings may be Made in Housekeeping: [...] With Variety of Curious Matters [...] The Whole Founded on Near Thirty Years Experience, London: Printed for James Hodges, at the Looking-glass, facing St. Magnus Church, London-Bridge; and B. Collins, bookseller, at Salisbury, OCLC 837728611, page 157:
  To make Capons […] [S]ome for this Purpoſe make it their Buſineſs after Harveſt-time to go to Markets for buying up Chickens, and between Michaelmas and All-hollantide caponize the Cocks, when they have got large enough to have Stones [i.e., testes] of ſuch a Bigneſs that they may be pulled out; for if they are too little, it can't be done; […]
(UK, Ireland, law, education) Ellipsis of Michaelmas term.

Christian feast