From Longman Dictionary of Contemporary EnglishMichaelmasMich‧ael‧mas /ˈmɪkəlməs/ noun [countable, uncountable] TMC29th September, a Christian holy day in honour of Saint Michael
Examples from the Corpus
Michaelmas• A department-wide graduate seminar is held during each Michaelmas and Hilary Term for the benefit of research students.• This evolved over a four-year period during our Michaelmas celebrations, which is when I first began to make it.• It worked its way to the outer island of Lewis where the Michaelmas tradition probably survived the longest. 