That part of a rocket motor that keeps the propellant grain in place.

A bend or dip in a soil drain which is always full of water, providing a water seal to prevent odors from entering the building.

An automatic transfer of control of a computer to a known location, this transfer occurring when a specified condition is detected by hardware.

1. A tuned circuit used in the radio-frequency or intermediate-frequency section of a receiver to reject undesired frequencies; traps in television receiver video circuits keep the sound signal out of the picture channel. Also known as rejector.

2. See <<wave trap>>

A sealed passage such as a U-shaped bend in a pipe or pump that prevents the return flow of liquid or gas.

See <<oil trap>>

A device which reduces the effect of the vapor pressure of oil or mercury on the high-vacuum side of a diffusion pump.

Any dark- colored, fine-grained, nongranitic, hypabyssal or extrusive rock. Also known as trappide; trap rock.

Any irregularity, such as a vacancy, in a semiconductor at which an electron or hole in the conduction band can be caught and trapped until released by thermal agitation. Also known as semiconductor trap.