O.E.
halig "holy," from P.Gmc.
*khailagas (cf. O.N.
heilagr, Ger.
heilig, Goth.
hailags "holy"), adopted at conversion for L.
sanctus. Primary (pre-Christian) meaning is not impossible to determine, but it was probably "that must be preserved whole or intact, that cannot be transgressed or violated," and connected with O.E.
hal (see
health) and O.H.G.
heil "health, happiness, good luck" (source of the Ger. salutation
heil). Use of
Holy Land for "western Palestine" dates to 1297.
Holy water was in O.E.
Holy smoke (1889),
holy mackerel (1903), etc., all euphemisms for
holy Christ. Phrase
holier-than-thou in reference to supercilious sanctimony first recorded 1912 in writings of Theodore Dreiser.