Architectural and Engineering Glossary


1.The quality or state of being per- ceivable by the eye.2.The distance at which an object out-of-doors can be just perceived by the eye.3.The size of a standard test object,observed under standardized viewing conditions,which has the same threshold as the given object.

Vision Cloth

A curtain on the stage of a theater which has a gauze or scrim inset;if an actor (or scene) behind the inset is illuminated,he is visible to the audience as one appearing in a vision. 

Vision Light

1.A window glazed with clear glass for viewing.2.A viewing window in a fire-rated door;usually wire glass must be used and the dimensions of the glass are limited by code.

Vision Light Door

A door having one small viewing window in the upper portion only,usually located on the vertical center line of the door.


glass See obscure glass.


In Spanish Colonial architecture in the American Southwest,a chapel in which services were conducted by a visiting padrebecause it served too few people to have its own priest.

Visor Roof

A pent roof,1 that extends only along one face of a building,usually the façade.


A usually unobstructed view into the distance;often given scale by the receding perspective of a road or a row of trees.

Visual Acuity

A measure of the ability to distinguish fine details;the reciprocal of the angular size of critical detail which is just large enough to be seen.

Visual Angle

The angle which an object or detail subtends at the point of observation;usually measured in minutes of arc.

Visual Field

The angular extent of space which can be perceived when the head and eyes are kept fixed.

Visual Inspection

Inspection by examination without the use of testing apparatus.

Visual Photometer

See photometer.


On drawings,abbr.for “vitreous.”


Descriptive of that degree of vitrification evidenced by low water absorption;generally signifies less than 0.3% absorption (except for floor and wall tile and low voltage electrical porcelain,for which it signifies less than 3.0% absorption).

Vitreous China

A ceramic that is glazed,vitrified,and extremely smooth.

Vitreous Enamel

See porcelain enamel.

Vitreous Sand

Same as smalt.

Vitreous Tile

Same as glazed tile.


Of a clay product,the condition resulting when kiln temperatures are sufficient to fuse grains and close the surface pores,making the mass impervious.


Same as vitreous.

Vitrified Brick

Brick which has been glazed so that it is impervious to water and has a high resistance to chemical corrosion.

Vitrified Clay Pipe

Pipe manufactured of an earthenware material which is glazed so that it is impervious to water and has a high resistance to chemical corrosion;in the US,sometimes used for house sewer pipes and underground drainage.

Vitrified Sewer Pipe

See vitrified clay pipe.

Vitruvian Scroll,Vitruvian Wave

A common motif in classical ornament:a series of scrolls connected by a wave-like band;also called a wave scroll or running dog.


An enclosure for raising animals and keeping them under observation.

Void Ratio

In a soil mass,or the like,the ratio of the volume of the void space to the volume of the solid particles.

Void-cement Ratio

The ratio of volume of air plus water to the volume of cement.

Void-solid Ratio

The proportion of window and door openings to wall surface area in the exterior wall of a building.


1.In cement paste,mortar,or  concrete,the air spaces between and within pieces of aggregate.2.Volumes of air not occupied by the solid material of a soil;voids usually are partially filled with air and water.


On drawings,abbr. for “volume.”


Descriptive of a substance which passes off easily as a gas or vapor,evaporating quickly. 

Volatile Thinner

A  thinner  which evaporates especially  rapidly,reducing the viscosity of a paint, adhesive,etc.,without altering its other properties.

Volcanic Tuff

See tuff.


In electric systems the unit of potential difference or electromotive force;when applied across a resistance of 1 ohm,will result in a current flow of 1 ampere.


Of an electric circuit,the greatest root mean square difference of potential between any two conductors of the circuit.

Voltage Drop

The difference in electromotive force between any two points in an electric circuit.

Voltage Regulator

An automatic electric control device whose output provides a constant voltage supply,even though the line voltage at its input may vary.

Voltage Transformer

A transformer whose primary is connected to a medium voltage source and whose secondary is connected to a load at lower voltage.


1.In a grounded electric circuit,the voltage between the given conductor and that point of the circuit which is grounded.2.In an ungrounded circuit,the greatest voltage between the given conductor and any other conductor in the circuit.


An instrument for measuring the voltage drop between any two points in an electric circuit.

Volume Batching

Measuring the constituent materials for mortar or concrete by volume,rather than by weight.

Volume Method

A method of estimating probable total construction cost by multiplying the adjusted gross building volume by a predetermined cost per unit volume.

Volume Strain

See bulk strain.

Volume Yield

See yield, 1.


1.An instrument for measuring the volume of a gas or liquid.2.A type of flushometer. 

Volumetric Absorption

The ratio of the volume of a liquid,that is absorbed by a mass to the volume of the mass.

Voluntary Standard

A standard with which there is no obligation to comply,either legally or de facto.


1.A spiral scroll,as on Ionic,Corinthian,or Composite capitals,or on consoles,etc.2.A stair crook having an easement with a spiral section of stair rail.


A vomitory in an ancient Roman theater or amphitheater.