n. (alsofelspar) Mineral. any of a group of aluminium silicates of potassium, sodium, or calcium, which are the most abundant minerals in the earth's crust. Derivatives:
feldspathic adj. feldspathoid n. Etymology: G Feldspat, -spath f. Feld FIELD + Spat, Spath SPAR(3): felspar by false assoc. with G Fels rock