surd

An irrational number, especially one expressed using the √ symbol.

A voiceless consonant.

Lacking the sense of hearing; deaf.

…how all Words fall to the Ground, spent upon such a surd and Earless Generation of Men, stupid unto all Instruction…

unheard

To this errour, of blending the ſurd and vocal modes of articulation together, may be added the too frequent uſe of compound articulations both vocal and ſurd.

Involving surds, or irrational numbers; not capable of being expressed in rational numbers.

a surd expression or quantity; a surd number

unvoiced; voiceless