adj unheard.
2. surd ·adj net having the sense of hearing; deaf.
3. surd ·noun a surd element of speech. ·see surd, ·adj, 4.
4. surd ·noun a quantity which can not be expressed by rational numbers; thus, ?2 is a surd.
5. surd ·adj involving surds; not capable of being expressed in rational numbers; radical; irrational; as, a surd expression or quantity; a surd number.
6. surd ·adj 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.