A clearly defined area or airspace designated for a particular purpose.

1. A portion of a track on a magnetic disk or a band on a magnetic drum.

2. A unit of data stored in such a portion.

Coverage of a radar as measured in azimuth.

A portion of a circle bounded by two radii and an arc joining their end points.

Something resembling the sector of a circle, as a warm sector between the warm and cold fronts of a cyclone.