sacred (adj.)

early 12c. as an adjective, seinte, "holy, divinely inspired, worthy of worship," used before proper names (Sainte Marian Magdalene, etc.), from Old French saint, seinte "holy, pious, devout," from Latin sanctus "holy, consecrated," past participle of sancire "consecrate" (see sacred). It displaced or altered Old English sanct, which is directly from Latin sanctus.

From an adjective prefixed to the name of a canonized person, it came to be used in English by c. 1200 as a noun, "a specific canonized Christian," also "one of the elect, a member of the body of Christ, one consecrated or set apart to the service of God," also in an Old Testament sense "a pre-Christian prophet."

It is attested by late 13c. as "moral or virtuous person, one who is pure or upright in heart and life."

The adjectives also were used as nouns in Late Latin and Old French: "a saint; a holy relic." The Latin word also is the source of Spanish santo, santa, Italian san, etc., and also ultimately the source of the word in most Germanic languages (Old Frisian sankt, Dutch sint, German Sanct).

Perhaps you have imagined that this humility in the saints is a pious illusion at which God smiles. That is a most dangerous error. It is theoretically dangerous, because it makes you identify a virtue (i.e., a perfection) with an illusion (i.e., an imperfection), which must be nonsense. It is practically dangerous because it encourages a man to mistake his first insights into his own corruption for the first beginnings of a halo round his own silly head. No, depend upon it; when the saints say that they—even they—are vile, they are recording truth with scientific accuracy. [C.S. Lewis, "The Problem of Pain," 1940]

1560s, "a law or decree," from Latin sanctionem (nominative sanctio) "act of decreeing or ordaining," also "a decree, an ordinance, a law," noun of action from past-participle stem of sancire "to decree, confirm, ratify, make sacred" (see saint (n.)).

Originally especially of ecclesiastical decrees. The extended sense of "express authoritative permission" is by 1720, hence the looser sense of "the conferring of authority upon (an opinion, practice or sentiment); confirmation of support derived from public approval" (1738). Moral sanction, in Bentham's philosophy, is "the knowledge of how one's neighbors will take a given act, as a motive for doing or not doing it" [Century Dictionary].

As "a penalty enacted according to a provision in a law to enforce obedience to it" from 1630s; in later 17c. also "a provision of a law which enforces obedience through rewards or penalties." Hence the modern sense of "economic or quasi-military action by a state against another," usually to enforce terms of a law or treaty that has been violated (1919).