Webster’s Revised Unabridged Dictionary · 1913 Lammas Lam′mas, n. [AS. hlāmmesse, hlāfmæsse, loaf mass, bread feast, or feast of first fruits; hlāf loaf + mæsse mass. See Loaf, and Mass religious service.] The first day of August; — called also Lammas day, and Lammastide. ‹ Lamm Lammergeir ›