directrix
[dih-rek-triks, dahy-]
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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
Usage note
See -trix.
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for directrix
Historical Examples of directrix
As necessary as the directrix is to the curve, so are the corresponding laws to the State.
The Romance of MathematicsP. Hampson
Directrix, a fixed line that is required for the description of a curve.
The New Gresham EncyclopediaVarious
Similarly, in an hyperbola a vertex is nearer 704 to the directrix than to the focus.
If a parabola roll on another parabola, their vertices coinciding, the focus of the first traces out the directrix of the second.
The Romance of MathematicsP. Hampson
With your permission I will add a few words to those I have already uttered with regard to the directrix.
The Romance of MathematicsP. Hampson
directrix
noun
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
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directrix
[dĭ-rĕk′trĭks]
The American Heritage® Science Dictionary
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