Martinmas

1. A Christian feast observed in commemoration of the death and burial of Saint Martin of Tours.
2. November 11, the day on which this feast is observed.

[Middle English martinmesse : Martin, Saint Martin of Tours + messe, masse, Mass; see Mass.]

This date, 11 November, is the feast of St Martin of Tours. In medieval and Elizabethan times it was an occasion for an ample feast of meat, because livestock which could not be fed through the winter was being slaughtered. Other joints were hung in the chimney to dry, like bacon, and were called Martlemas beef (or mutton). It was regarded as the end of the farming year, and in many places hiring fairs were held for farm-workers who wished to change jobs.

In some areas, it was said that the weather on this date foretold that of the coming winter. In others, this could be deduced from markings on the breast-bone of a goose eaten on Matinmas Eve; white marks meant snow and dark ones hard frost, while the front part of the bone meant before Christmas and the back part afterwards.

The noun has one meaning:

Meaning #1: the feast of Saint Martin; a quarter day in Scotland
  Synonyms: St Martin's Day, November 11