Definitions for lammas day
Lammas, Lammas Day, August 1(noun)
commemorates Saint Peter's miraculous deliverance from prison; a quarter day in Scotland; a harvest festival in England
The Nuttall Encyclopedia
the first of August, literally "the loaf-mass" day or festival day at the beginning of harvest, one of the cross quarter days, Whitsuntide, Martinmas, and Candlemas being the other three.