Surd

Surd may refer to:

Mathematics

 * Surd (mathematics), an unresolved root or sum of roots
 * Radical symbol, the notation for a root
 * formerly, an irrational number in general

Other uses

 * Surd, Hungary
 * Voiceless consonant, opposed to sonant
 * Jeremiah Surd, a character on the television series The Real Adventures of Jonny Quest