A specific, demarcated portion of a lot of a substance that is to be chemically analyzed.

1. A single section of an overlay program structure, which can be loaded into the main memory when and as needed.

2. In some direct-access storage devices, a hardware-defined portion of a track having fixed data capacity.

1. A segment of a line or curve is any connected piece.

2. A segment of a circle is a portion of the circle bounded by a chord and an arc subtended by the chord. A segment of a totally ordered Abelian group G is a subset D of G such that if a is in D then so are all elements b satisfying - a ≤ b ≤ a.

In air operations, a basic functional division of an instrument approach procedure; it bears a fixed orientation with respect to the course to be flown; it is assigned specific geometric coordinates which uniquely determine its position; the location of the segment is assigned with respect to the obstacles in the operations area.