/serrd/ , adj.
1. Phonet. voiceless (opposed to sonant ).
2. Math. (of a quantity) not capable of being expressed in rational numbers; irrational.
n.
3. Phonet. a voiceless consonant (opposed to sonant ).
4. Math. a surd quantity.
[ 1545-55; surdus dull-sounding, mute, deaf ]