Meaning of SURD in English

SURD

adj. & n.

--adj.

1. Math. (of a number) irrational.

2 Phonet. (of a sound) uttered with the breath and not the voice (e.g. f, k, p, s, t).

--n.

1. Math. a surd number, esp. the root of an integer.

2 Phonet. a surd sound.

Etymology: L surdus deaf, mute: sense 1 by mistransl. into L of Gk alogos irrational, speechless, through Arab. jadr asamm deaf root

Oxford English vocab.      Оксфордский английский словарь.