from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any of a small group of igneous, plutonic, and volcanic minerals formed in magma that did not contain enough silica to satisfy all the chemical bonds. Feldspathoids are silica-poor variants of the feldspar group.
- adj. Resembling a feldspar.
from The Century Dictionary and Cyclopedia
- n. Feldspar or some other species (nephelite, sodalite, leucite, and the scapolites) which plays a similar part in the composition of rocks.
Feld, field (from Middle High German veld, from Old High German feld) + Spath, spar + Oid, like or resembling. (Wiktionary)