surd

adjective

1. Math. irrational
2. Phonet. voiceless ()

Origin: L surdus, deaf, dull, mute: used to transl. Gr alogos, irrational, lit., without reason

noun

1. Math. an irrational number or quantity; specif., a root which can be expressed only approximately: is a surd
2. Phonet. a voiceless sound