Architectural and Engineering Glossary


M.b.m., MBM

In the lumber industry,abbr.for “thousand (feet) board measure.”

Macadam Aggregate

A product manufactured by crushing stone, slag, or gravel and then screening it to a uniformly coarse size; when compacted, void spaces are relatively large.

Macadam, Tarmac, Tarmacadam

1.A paving for roads or other surfaces, formed by  grading and compacting layers of crushed stone or gravel; then the top layer(s) are usually bound by asphaltic material, acting to stabilize the  stone, provide a smoother surface, and seal against water penetration. 2.The crushed stone used in a macadamized surface.

Macassar Ebony

A hard, very heavy wood of the East Indies; black with red or brown streaks; used for decorative paneling and applications requiring high impact or wear resistance.


A Roman meat or produce market in a covered hall.


 In ancient Roman construction, a rough wall having no facing; constructed in a wide variety of materials.


An overhanging defensive structure at the top of a medieval fortification, with floor openings through which boiling water or oil, missiles, etc., could be dropped on attackers.

Machine Bolt

A threaded bolt having a straight shank and a conventional head such as a square, hexagonal, button, or countersunk type.

Machine Burn

A  darkening or charring of a surface due to overheating of the cutting knives or abrasive belts during machining of the material.

Machine Gouge

A groove which results when a machine cuts below the desired line of cut. 


Visible to the unaided eye.

Made Ground, Made-up Ground.

1.Solid ground formed by filling in an artificial or natural pit with hard rubble such as broken brick, concrete, etc., or with rubbish.


A theological school, generally arranged around a courtyard, from the 11th cent.A.D. on, in Anatolia, Persia, and Egypt.


1.In ancient Rome, a balcony or gallery for spectators at a public show. 2.Originally, the balcony in the Forum at Rome, for spectators of the gladiatorial combats.


A storage place for ammunition and explosives; also see powder house.

Magazine Boiler

A coal or coke fired boiler (in a hot-water or central heating system) which has a bunker fitted to it, large enough to contain 24 hours of fuel.


A fine white powder of magnesium oxide; gives brick a yellow tint.

Magnesia Insulation

Magnesium carbonate hydroxide, with or without admixture of fiber reinforcement or other materials; a good thermal insulator because of the great number of closed air cells it contains; molded into rigid boards, blocks, or shapes conforming to piping.


A natural magnesium carbonate.

Magnesite Flooring

A flooring material composed of calcined magnesite, magnesium chloride, sawdust, ground quartz or silica, and fine powdered wood waste; used as a finishing surface on concrete floor slabs.


A gray white, light metal (64% the weight of aluminum); easily drawn and machined; immune to alkalies.

Magnesium Alloy

Any of a number of alloys  of magnesium; the usual additives are aluminum, manganese, silicon, silver, thorium, and zirconium, used singly or in combination.

Magnesium Hydroxide

A white powder which is slightly soluble in water; in dolomitic type limes used in plaster, its presence helps the lime to spread more easily.

Magnesium Lime

Lime manufactured from limestone; contains some magnesium; used as finish lime in plastering or as mason’s lime in mortar. 

Magnetic Bearing

The bearing, 4 of a line where the reference meridian is the local magnetic meridian.

Magnetic Catch

A door catch that uses a magnet to hold the door in a closed position.

Magnetic Declination

At a particular location, the horizontal angle between true meridian (true north-south line) and magnetic meridian (direction of compass needle).

Magnetic Switch

An electric switch whose switch contacts are controlled by means of an electromagnet; esp. used in the control circuits for motors.


A natural black oxide of iron, containing from about 65 to 72% iron and some times a small amount of nickel and titanium; used as an aggregate in high density concrete.


A  stick used  by painters as a rest for the hand while painting. 


1.A straight grained wood of intermediate density, pinkish to red brown in color; found principally in the West Indies, and Central and South America. Used primarily for interior cabinetwork and decorative paneling. 2. Wood from a number of tropical species which resemble mahogany, generally classified as to origin, i.e., African mahogany, Philippine mahogany, etc.

Maiden Tower

The keep or principal tower of a castle.


An instrument for the measure- ment of pressure;a U-shaped glass tube partially filled with water or mercury,one side of which is connected to the source of pressure.The amount of displacement of the liquid is a measure of the magnitude of the pressure.

Manor House

1.Usually, an imposing house in a countryside,often the residence of a land owner with considerable acreage.2.A relatively simple one room house of early colonists in America,having a gable roof,clapboard walls,a battened door,a window at the front of the house with solid shutters,and a chimney at one or at each end.

Mansard Style

1.A term sometimes used as a synonym for Second Empire style in the United States.2.An architectural style that makes use of,or suggests,a mansard roof.


The dwelling of a clergyman.


1.A very large,imposing,stately residence.2.In colonial times,the residence of a landholder.3.A manor house;also called a mansion house.


1.A beam or arch that supports the masonry above a fireplace;also called a mantel tree.2.All the construction or facing around a fireplace.3.A mantelshelf.

Mantel Board

A wood mantelshelf.

Mantel Register, Cast-iron Register

A relatively inexpensive prefabricated cast iron man telpiece which screws onto the fireplace and forms the fireplace surround.


That part of a mantelpiece which constitutes a shelf.


A wood,stone,or iron structural member that spans the opening over a fireplace.Often,a large horizontal oak timber that serves to support the wall construction above,typically placed high enough above the hearth to prevent its igniting;sometimes plastered to improve its fire resistance.


1.Same as mantel.2.The outer covering of a wall which differs from the material of the inner surface.


Same as chemise.


A  fireproofing plaster omposed of equal parts of gypsum and exfoliated vermiculite;applied to structural steel elements as fireproofing.


A short narrow section of corridor purposely constructed to permit passage by only one person;has interlocking doors at both ends;used in some high level security installations.

Manual Batcher

A batcher equipped with gates or valves which are operated manually. 

Manual Call Point

A British term for fire alarm box.

Manual Fire Alarm System

A fire alarm system that is manually operated,so arranged that the operation of any one station will ring all signals throughout the building as well as at one or more selected locations.

Manual Fire Pump

A pump supplying water to a sprinkler or standpipe system which is not activated automatically and must be started by hand.