The amount by which the threshold of audibility of a sound is raised by the presence of another sound; the unit customarily used is the decibel. Also known as audio masking; aural masking.

1. Replacing specific characters in one register by corresponding characters in another register.

2. Extracting certain characters from a string of characters.

1. Using a covering or coating on a semiconductor surface to provide a masked area for selective deposition or etching.

2. A programmed procedure for eliminating radar coverage in areas where such transmissions may be of use to the enemy for navigation purposes, by weakening the beam in appropriate directions or by use of additional transmitters on the same frequency at suitable sites to interfere with homing; also used to suppress the beam in areas where it would interfere with television reception.

Preventing entrance of a tracer gas into a vessel by covering the leaks.