perissad
noun
pe·ris·sad
pəˈrisəd,
-iˌsad
plural -s
1
obsolete : an element or radical of odd valence
2
: an element of odd atomic number —contrasted with artiad
Word History
Etymology
Greek perissos beyond the regular number or size, superfluous, excessive, uneven (from peri around, beyond) + English -ad