What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
An abundant rock-forming mineral typically occurring as colorless or pale-colored crystals and consisting of aluminosilicates of potassium, sodium, and calcium.
Mid 18th century: alteration of German Feldspat, Feldspath, from Feld ‘field’ + Spat, Spath ‘spar’ (see spar). The form felspar is by mistaken association with German Fels ‘rock’.