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.
... for it is not for nothing that the apostle calleth religion "our reasonable service of God;" insomuch as the very ceremonies and figures of the old law were full of reason and signification, much more than the ceremonies of idolatry and magic, that are full of non-significants and surd characters. But most specially the Christian faith, as in all things so in this, deserveth to be highly magnified; holding and preserving the golden mediocrity in this point between the law of the heathen and the law of Mahomet, which ... — The Advancement of Learning • Francis Bacon
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