Of a doorway, having jambs which are inclined slightly inward, so that the opening is wider at the threshold than at the top.

Related Terms


A valve in which the force of compressed air against a diaphragm is opposed by the force of a spring to control the area of the opening for a fluid stream.


A variable-area flowmeter in which a tapered plug, located in an orifice and raised until the resulting opening is sufficient to handle the fluid flow, is used to measure the flow rate.


A small door in a furnace with a glass opening through which combustion may be observed.


An equipment container with a parachute which is capable of opening automatically after a delayed drop.


A cylindrical fishing tool having the open bottom end fitted with an inward opening valve.


1. An opening in a wall or ceiling with slanted or sloping slats to allow sunlight and ventilation and exclude rain; may be fixed or adjustable, and may be at the opening of a ventilating duct. Also known as outlet ventilator. 2. Any arrangement of fixed or adjustable slatlike openings to provide ventilation.


A device to apportion the output of granulated or powdered solids at a constant rate from a feed hopper; weight-measured decrease in hopper content actuates further opening of the discharge chute to compensate for flow loss as the hopper overburden decreases; used in the chemical, fertilizer, and plastics industries.


1. The depth of liquid above an opening from which gas or vapor issues, as for a riser in a distillation-column tray. 2. Product drawoff in which a depth of liquid prevents the outflow of gas or vapor.


An opening cut into a strengthening member that decreases its weight without significantly altering its strength.


In masonry work, a rectangular brick having one corner cut diagonally to half the end of the brick and used to fill an opening in a course larger than half a brick. Also known as beveled closer.

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