Architectural and Engineering Glossary

Old Wood

Wood which has been worked previously and is reused.


A lightweight,high strength,long chain polymeric material having very good abrasion resistance;especially used in indoor outdoor carpeting.


A natural resin containing essential oils;used in adhesives,varnishes,and various compounds.

Oleoresinous Varnish

A varnish consisting of a drying oil compounded with a hardening resin.

Olive Butt

Same as olive knuckle hinge.

Olive Hinge

Same as olive knuckle hinge.

Olive Knuckle Hinge

A paumelle hinge with knuckles forming an oval shape.

Olmec Architecture

Architecture of the most ancient civilization of Mesoamerica (1500–400 B.C.) usually characterized by:a north south orientation of the ceremonial center,stepped pyramids,sloping walls,ceremonial courtyards,and platforms on which to construct temples.

Omnidirectional Microphone

A microphone which is equally sensitive in all directions.

On Condition Maintenance

Maintenance of machinery when condition monitoring equipment indicates that a mechanical failure is about to occur.


Same as center to center.


Decorations executed with enamel on ceramic glaze and then fired in a kiln in which heat alone,not flames,is permitted to enter.

One Centered Arch

Any arch struck from a single center,such as a round,segmental,or horseshoe arch.

One Part Adhesive.

An adhesive that sets without the addition of a catalyst or hardener.

One Pour System.

A batch of concrete that is completely poured at a single time.Compare with two pour system.

One Room Cottage.

A cottage having a one room plan,usually with a loft space above.

One Room Plan.

The earliest and simplest floor plan for a dwelling, especially used in 17th century and beyond; consisted of a single room,usually called a hall or keeping room,that served as a combination living room, dining room,kitchen,and workroom;cooking was done in a large fire place set into a massive chimney. In some regions, the front door of the house opened into a small vestibule called a porch,but in other regions, the door opened directly into the hall;access to a loft above was provided either by a staircase in the vestibule or by a ladder in the hall.Many such houses were enlarged by the addition of a second room at ground level,called the parlor,giving rise to the hall and parlor plan;the parlor served as a combination living room and sleeping room for the parents.Also see one over one, 1.

One Room Schoolhouse.

A school in which all elementary grade students were once taught in a single room.Such schools were common in sparsely populated areas before the 20th century;many had a bell at the ridge of the roof for summoning students at the start of the school day.

One Sided Connection

A connection of one structural member to a second which is not symmetrical about the component part of the member being connected.

One Time Fuse.

Same as nonrenewable fuse.

One Way System.

In reinforced concrete,a system of steel reinforcement within a slab that is assumed to bend in one direction only.


See story and a half.

One-and-one-half-bay Cottage

Same as three quarter Cape Cod house.

One-and-one-half-story House

A one story house having a loft space between the ceiling of the first floor and the roof directly above;windows in the gable end walls and/or dormers provide light and ventilation in this loft space,providing the additional half story.

One-line Diagram

A representation of an electrical system by means of single lines and graphic symbols showing the major components of the system.


1.A two story cottage having two rooms,one directly over the other;usually the result of the expansion of a cottage having a one room plan by the addition of a floor above it.2.A term descriptive of a double hung window having one pane in the upper sash and one pane in the lower;see pane.

One-pipe Heating

A heating system in which a centrally located heater distributes hot water serially to individual heaters in a home or office building.

One-pipe System

A plumbing system in which a single pipe carries both soil and waste.

One-way Joist Construction

A type of framing system for floors or roofs in a concrete building;consists of a series of parallel joists which are supported by girders (perpendicular to the joists) between columns.

One-way Slab

A rectangular reinforced concrete slab which spans a distance very much greater in one direction than the other;under these conditions,most of the load is carried on the shorter span.

One-way Throw

A supply grille that deflects the outgoing air in one direction only.