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surd

Pronunciation: /səːd/

Definition of surd

adjective

1 Mathematics (of a number) irrational.

2 Phonetics (of a speech sound) uttered with the breath and not the voice (e.g. f, k, p, s, t).

noun

1 Mathematics a surd number, especially the irrational root of an integer.

2 Phonetics a surd consonant.

Origin:

mid 16th century: from Latin surdus 'deaf, mute'; as a mathematical term, translating Greek (Euclid) alogos 'irrational, speechless', apparently via Arabic jiḏr aṣamm, literally 'deaf root'. surd (sense 2 of the adjective) dates from the mid 18th century