- Irrational quantity - Net having the sense of hearing; deaf. - Unheard. - Involving surds; not capable of being expressed in rational
numbers; radical; irrational; as, a surd expression or quantity; a surd
number. - 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. - A quantity which can not be expressed by rational numbers;
thus, Ã2 is a surd. - A surd element of speech. See Surd, a., 4.