[ dih-rek-triks, dahy- ]
/ dɪˈrɛk trɪks, daɪ- /

noun, plural di·rec·trix·es, di·rec·tri·ces [dih-rek-tri-seez, dahy-, dahy-rek-trahy-seez] /dɪˈrɛk trɪˌsiz, daɪ-, ˌdaɪ rɛkˈtraɪ siz/.

Geometry. a fixed line used in the description of a curve or surface.
Archaic. a directress.

Origin of directrix

From New Latin, dating back to 1615–25; see origin at direct, -trix

Usage note

See -trix. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for directrix

British Dictionary definitions for directrix


/ (dɪˈrɛktrɪks, daɪ-) /


geometry a fixed reference line, situated on the convex side of a conic section, that is used when defining or calculating its eccentricity
a directress

Word Origin for directrix

C17: New Latin, feminine of director
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for directrix


[ dĭ-rĕktrĭks ]

A straight line used in generating a curve such as a parabola.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.