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Term Definition

A caulking material made from hemp fibers treated with tar.


Interval between two sounds having a basic frequency ratio of two. The formula is 2n times the frequency, where n is the desired octave interval. The octave band frequency given in sound test results is usually the band center frequency, thus the 1000 Hz octave band encompasses frequencies from 707 Hz to 1414 Hz (n = ± 1/2). The 1000 Hz one-third-octave band encompasses frequencies from 891 Hz to 1122 Hz (n = ± 1/6).

Oil-Based Paint

Paint composed of resins requiring solvent for reduction purposes.

Opaque Coatings

Coatings that completely obscure the color and much of the texture of the substrate.

Open Drainage

The removal of unwanted water by means of surface devices.

Open-Web Joist

A prefabricated steel truss made of welded members, used for floor and roof construction.

Organic Material

A class of compounds comprising only those existing in plants and animals.

Oriented Strand Board

A panel made from wood strands that have their strand face oriented in the long direction of the panel.

Outlet Box

A box that is part of the electrical wiring system that contains one or more receptacles.

Overlaid Plywood

Plywood panels whose exterior surfaces are covered with a resin-impregnated fiber ply.


The operation of electrical equipment in excess of the normal full-loaded electrical rating or of a conductor carrying current in excess of its rated capacity.


A reaction between a material and oxygen in the atmosphere.

Oxide Layer

In aluminum, a very thin protective layer formed naturally on aluminum due to its reaction to oxygen.


To convert an element into oxide, such as rusting steel.

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