A central line, an axis; spec. the equator; (formerly) the ecliptic; (Mathematics) a bisecting line. Cf. middle line, n. 1.

Geometry. A line that cuts another; esp. a straight line that cuts a curve in two or more parts.

Mathematics. The action of dividing a line into parts. golden section, also medial section, median section: the division of a line in extreme and…

= bisector, n.; spec. in biaxial polarization, the line bisecting the angle between the two axes of polarization (= linea bisectrix).

Geometry. (See quot. 1857).

The property or fact of being secant.

Geometry. A line intersecting two or more lines, or a system of lines.