A region not adequately covered by the main lobes of a radar antenna.

A uniformly magnetized area in a magnetic storage device (tape, disk), used to indicate the end of an area containing information.

The spacing between two electric contacts.

A break in a closed magnetic circuit, containing only air or filled with a nonmagnetic material.

A short region that is missing in one strand of a double-stranded deoxyribonucleic acid.

Any sharp, deep notch in a mountain ridge or between hills.

An opening at the point of closest approach between faces of members in a weld joint.