directrix noun. [dɪ'rɛktrɪks, dʌɪ-] Pl. -trices [-trɪsi:z]. E16.
[medieval Latin, fem. of late Latin DIRECTOR: see -TRIX.]
1. = DIRECTRESS. E16.

2. Geometry. A fixed line with reference to which a curve or surface is defined; spec. the straight line the distance of which from any point on a conic bears a constant ratio to the distance of the same point from the focus. E18.

[TahlilGaran] English Dictionary ▲