Lunette: a space somewhat resembling a half-moon, with the curve uppermost. Especially the wall-space, enclosed by the ends of a barrel-vault; or by the wall-arch of a groined or rib vault.
Lych-Gate (lit. “corpse-gate”): covered gateway at entrance to a churchyard, where the coffin rests during the first portion of the burial service.
[M]achicolation: the opening between a wall and a parapet, when the latter is built out on Corbels (which see). Through it missiles or burning liquids could be showered upon assailants.
Mansard or Mansart: applied to roofs which have a hip or angle—instead of a continuous slope—on all four sides. Named after the French architect who popularised, though he did not invent, it.
Mastaba: an Egyptian tomb, so-called from its construction resembling the ordinary Egyptian bench, which is composed of a horizontal board, supported upon boards that slope inward toward the seat.
Mausoleum (mō-so-lée-um): tomb of more than ordinary size and architectural pretensions. So called from the tomb erected at Halicarnassus in 325 B.C., in memory of Mausolus, King of Caria, by his widow, Artemisia.
Megalith (lit. huge stone): Megalithic, composed of such. See Cyclopean.
Megaron: Homeric word for palace or large hall.
Member (lit. limb): any component part of a structural design that has a specific function to perform.
Menhir: a prehistoric monument, consisting of a single rough or rudely shaped stone, usually of large size (megalithic); perhaps originally connected with fetish worship, to ward off evil spirits; then as a memorial of a dead chieftain or a victory. The prototype of the Obelisk.