Middiameter

Middiameter is a term that appears in some geometric writings and older mathematical literature. Unlike the standard concept of a diameter, which is the greatest distance across a circle or sphere and the line segment through its center, middiameter does not have a single universally accepted definition in modern usage. In practice, its meaning is highly context-dependent and varies by author.

In various sources middiameter has been used to describe a diameter that is in a central or mid-position relative to other reference directions or features. For example, a middiameter may refer to the diameter through the center that bisects a particular region, chord, or pair of parallel supporting lines. In other readings, middiameter denotes a diameter associated with a central or mean value—such as a circle whose radius is the arithmetic mean of a set of radii tied to the same figure.

Because middiameter is not standardized, readers should consult the specific source to understand how the term is defined in that text. The term is sometimes discussed alongside related concepts such as diameter, mean diameter, width, and midline in convex geometry or in discussions of approximating figures by circles.

See also: Diameter; Mean diameter; Width; Midline; Circle.