During the
Middle Ages, when
Catholicism permeated
Europe, the idea that God would protect you extended beyond the
church building (the practice of naming a church after a venerated
martyr or
saint went back to the 4th century) to all aspects of life: your family, your
house, your city, your
kingdom, your trade.
Those that had gone before you into
heaven were called upon in prayers to
intercede on your behalf.
Saints, in particular, were looked to for protection, and so it was that
monasteries,
convents, military units,
guilds, towns, charities, and events each came to adopt an
intercessor.
The saint designated the protector and guardian of the persons, places, or things under his or her purview:
St. George is the patron saint of Barcelona, St. Dymphna is the patron saint of sleepwalkers, St. Isidore is the patron saint of the internet.
Patron Saints A-G - Patron Saints H-N - Patron Saints O-Z
Saints were chosen sometimes based on an actual connection between the saint and his or her protectee (As her martyrdom included having all her teeth broken, St. Apollonia is the patron saint of toothaches), but they might also be chosen merely for their piety or for a play on words (St. Expeditus, an early martyr, is prayed to for urgent matters). Different locations in Europe might have differing patron saints for the same subject, leading Rome to issue proclamations to sort out the official patrons.
In the
nonprofit world, a
nickname for a
donor or
volunteer (
patron) who makes an especially
generous contribution.
Sources:
Parkinson, Henry. "Patron Saints." The Catholic Encyclopedia, Volume XI. 1911. <http://www.newadvent.org/cathen/11562a.htm> (24 October 2002)