• synonyms


See more synonyms for surd on Thesaurus.com
  1. Phonetics. voiceless (opposed to sonant).
  2. Mathematics. (of a quantity) not capable of being expressed in rational numbers; irrational.
Show More
  1. Phonetics. a voiceless consonant (opposed to sonant).
  2. Mathematics. a surd quantity.
Show More

Origin of surd

First recorded in 1545–55, surd is from the Latin word surdus dull-sounding, mute, deaf
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for surd

surd, dumb, inarticulate, mum, mute, silent, speechless, aphonic

Examples from the Web for surd

Historical Examples of surd

  • Of course this gives a number, but this number may be a surd, like √2.

    The Teaching of Geometry

    David Eugene Smith

  • For 'voiceless,' 'surd,' 'hard,' or 'tenuis' are sometimes used.

    New Latin Grammar

    Charles E. Bennett

  • On the one hand Aristotle by his doctrine of matter admitted a surd into his system.

  • The rule of surd to surd and sonant to sonant is neglected in most of the factitious specimens of broken English.

    Pennsylvania Dutch

    S. S. Haldeman

  • The Sanskrit terms sonant and surd are, in a scientific point of view, the least exceptionable.

    The English Language

    Robert Gordon Latham

British Dictionary definitions for surd


  1. maths an expression containing one or more irrational roots of numbers, such as 2√3 + 3√2 + 6
  2. phonetics a voiceless consonant, such as (t)
Show More
  1. of or relating to a surd
Show More

Word Origin for surd

C16: from Latin surdus muffled
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

Word Origin and History for surd


1550s, "irrational" (of numbers), from Latin surdus "unheard, silent, dull," possibly related to susurrus "a muttering, whispering" (see susurration). The mathematical sense is from the use of Latin surdus to translate Arabic (jadhr) asamm "deaf (root)," itself a loan-translation of Greek alogos, literally "speechless, without reason" (Euclid book x, Def.). In French, sourd remains the principal word for "deaf."

Show More
Online Etymology Dictionary, © 2010 Douglas Harper