(arithmetic) An irrational number, especially one expressed using the √ symbol. / (linguistics) A voiceless consonant.

(obsolete) Lacking the sense of hearing; deaf. / (obsolete) unheard / (mathematics) Involving surds, or irrational numbers; not capable of being expressed in rational numbers.

plural of surd

(mathematics) An irrational number that is the solution of a quadratic equation of the form ax²+bx+c=0, where a, b, and c are integers and a ≠ 0.

(obsolete) deafness / (obsolete, linguistics) voicelessness

(obsolete) A sardine.

(phonetics) devoicing