noun (plural directrices /-trɪsiːz/)Geometry
A fixed line used in describing a curve or surface.
More example sentences
- In the following, the feet of perpendiculars dropped from points A, B, etc. on the parabola to the directrix will be denoted A ’, B ’, etc.
- The focus and directrix of a hyperbola were considered by Pappus.
- The directrix is used in the construction, which follows, mutatis mutandis, the same course as the above construction in the case of the ellipse.
early 18th century: from medieval Latin, literally 'directress', based on Latin dirigere 'to guide'.
Definition of directrix in:
- The US English dictionary