surd /ˈsɝd/
 (a.)無理數的,不盡根的,清音的無理數,不盡根數,清音


 Surd, n. Math.
 1. A quantity which can not be expressed by rational numbers; thus, √2 is a surd.
 2. Phon. A surd element of speech. See Surd, a., 4.

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 Surd a.
 1. Net having the sense of hearing; deaf. [Obs.] “A surd . . . generation.”
 2. Unheard. [Obs.]
 3. Math. Involving surds; not capable of being expressed in rational numbers; radical; irrational; as, a surd expression or quantity; a surd number.
 4. Phonetics Uttered, as an element of speech, without tone, or proper vocal sound; voiceless; unintonated; nonvocal; atonic; whispered; aspirated; sharp; hard, as f, p, s, etc.; -- opposed to sonant. See Guide to Pronunciation, §§169, 179, 180.


 surd
      adj : of speech sounds [syn: voiceless, unvoiced] [ant: sonant]
      n : a consonant produced without sound from the vocal cords
          [syn: voiceless consonant]