c.1125, from O.Fr.
seinte, altering O.E.
sanct, both from L.
sanctus "holy, consecrated" (used as a noun in L.L.), prop. pp. of
sancire "consecrate" (see
sacred). Adopted into most Gmc. languages (cf. O.Fris.
sankt, Du.
sint, Ger.
Sanct). Originally an adj. prefixed to the name of a canonized person; by c.1300 it came to be regarded as a noun.
"Saint - A dead sinner revised and edited. The Duchess of Orleans relates that the irreverent old calumniator, Marshal Villeroi, who in his youth had known St. Francis de Sales, said, on hearing him called saint: 'I am delighted to hear that Monsieur de Sales is a saint. He was fond of saying indelicate things, and used to cheat at cards. In other respects he was a perfect gentleman, though a fool.' " [Ambrose Bierce]
Meaning "person of extraordinary holiness" is recorded from 1563. The verb meaning "to enroll (someone) among the saints" is attested from 1375. Applied widely to living things, diseases, objects and phenomena, e.g.
Saint Bernard, the breed of mastiff dogs (1839), so called because they were used by the monks of the hospice of the pass of St. Bernard (between Italy and Switzerland) to rescue snowbound travelers;
St. Elmo's Fire "corposant" (1561) is from It.
fuoco di Sant'Elmo, named for the patron saint of Mediterranean sailors, a corruption of the name of
St. Erasmus, an Italian bishop martyred in 303.
[seyn-tid] 
