I. ˈsərd, ˈsə̄d, ˈsəid adjective
Etymology: Latin surdus dull-sounding, silent, deaf; akin to Latin susurrus hum, murmur — more at swarm
1. : lacking sense : lacking reason or rationale : insensate , irrational
the surd mystery and the strange forces of existence — D.C.Williams
2. : voiceless — used of speech sounds; opposed to sonant
II. noun
( -s )
: one that is surd: as
a. : an irrational radical with rational radicand
√3 and √ 2/5 are surds
b. : a surd speech sound
c. : an unknown or irrational quality
the uncharted surd at the heart of European politics — William Barrett