surd

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surd

/sɜːd/ Australia, UK
/sɝd/ US
/sʌɹd/ Scotland
/søːd/ New Zealand
/seːd/
/sɛːd/

Sounds like sirred · Rhymes with -ɜː(ɹ)d

Where it comes from

First attested in the mid 16th century from Latin surdus (“deaf, mute”), used in mathematics for “irrational,” reflecting ἄλογος (álogos, “irrational, speechless”) as found in Euclid, apparently transmitted via Arabic جِذْر أَصَمّ (jiḏr ʔaṣamm, “deaf root”). The phonetic sense, “voiceless,” emerged in the 18th century. Doublet of surdo.

noun surds

An irrational number, especially one expressed using the √ symbol.
A voiceless consonant.
Opposite: sonant

adjective more surd · most surd

obsolete Lacking the sense of hearing; deaf. …how all Words fall to the Ground, spent upon such a surd and Earless Generation of Men, stupid unto all Instruction…
obsolete unheard To this errour, of blending the ſurd and vocal modes of articulation together, may be added the too frequent uſe of compound articulations both vocal and ſurd.
Involving surds, or irrational numbers; not capable of being expressed in rational numbers. a surd expression or quantity; a surd number
unvoiced; voiceless
Opposite: sonant

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MLA

"surd." Wiktionary, via Micwyn, micwyn.com/word/surd. Accessed 6 Nov. 2026.

APA

surd. (n.d.). In Wiktionary, via Micwyn. Retrieved November 6, 2026, from https://micwyn.com/word/surd

Chicago

"surd." Wiktionary, via Micwyn. Accessed November 6, 2026. https://micwyn.com/word/surd.

BibTeX

@misc{surd_2026,
  title = {surd},
  howpublished = {Wiktionary, via Micwyn},
  year = {2026},
  url = {https://micwyn.com/word/surd},
  urldate = {2026-11-06}
}