surd
adjEtymology 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.
1
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…1670s, published 1716, Thomas Browne, Christian Morals, part 3, section 6
2
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.1773, William Kenrick, A New Dictionary of the English Language, section 3, page 5:
3
Mathematics, Sciences Involving surds, or irrational numbers; not capable of being expressed in rational numbers.
- a surd expression or quantity; a surd number
4
Human sciences, Linguistics, Phonetics, Phonology, Sciences unvoiced; voiceless
- Derived terms
- surdity, surdization
- Related terms
- absurd