Lamen (Latin, “plate”), in ceremonial magic, is a symbolic breastplate worn on the chest, supported by a ribbon, collar, or cord around the neck. In the Kabbalah traditions of magic, the use of the lamen represents the forces of Tiphareth, the central unifying Sephirah of the Tree of Life, and carries the the corresponding symbolism in one form or another. In practicing the magical evocation, the sigil of the spirit to be evoked is sometimes worn as the lamen representing the power of the magician over the spirit. A Rose Cross Lamen was used in the Hermetic Order of the Golden Dawn.
The Abramelin system uses the lamen in a different sense; here it is a silver plate on which the Holy Guardian Angel writes letters in formed of dew. A.G.H.
Greer, John Michael. The New Encyclopedia of the Occult. St. Paul. MN. Llewellyn Worldwide. 2005. p. 266