holy [OE] Holy is related to Dutch and German heilig, and derives from the same root as whole. The holy of holies [LME] originally referred to the inner chamber of the sanctuary of the Jewish temple in Jerusalem, which was separated by a veil from the outer chamber and entered only by the High Priest on the Day of Atonement. The attitude of self-conscious virtue or piety that is holier than thou [E20th] also has a biblical source, in Isaiah, which deplores ‘a rebellious people…Which say, Stand by thyself, come not near to me; for I am holier than thou’. See also high.