Pronunciation: (sûrd), [key]
1. Phonet.voiceless (opposed to sonant).
2. Math.(of a quantity) not capable of being expressed in rational numbers; irrational.
1. Phonet.a voiceless consonant (opposed to sonant).
2. Math.a surd quantity.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.