The Collaborative International Dictionary
Perissad
Perissad \Per"is*sad\, a. [Gr. ? odd, from ? over.] (Chem.) Odd; not even; -- said of elementary substances and of radicals whose valence is not divisible by two without a remainder. Contrasted with artiad.
Wiktionary
perissad
a. (context chemistry English) odd; not even; said of elementary substances and of radicals whose valence is not divisible by two without a remainder.