"small chapel for prayer or worship," early 14c., oratorie, from Old French oratorie and directly from Late Latin oratorium "place of prayer" (especially the Oratory of St. Philip Neri in Rome, where musical services were presented; see oratorio), noun use of an adjective, as in oratorium templum, from neuter of Latin oratorius "of or for praying," from ōrare "to pray, plead, speak" (see orator).
"formal public speaking; the art of eloquence," 1580s, from Latin (ars) oratoria "oratorical (art)," fem. of oratorius "of speaking or pleading, pertaining to an orator," from ōrare "to speak, pray, plead" (see orator).
Oratory is the art or the act of speaking, or the speech. Rhetoric is the theory of the art of composing discourse in either the spoken or the written form. Elocution is the manner of speaking or the theory of the art of speaking ...: the word is equally applicable to the presentation of one's own or of another's thoughts. [Century Dictionary]
1796 in reference to members of a secret politico-religious society founded 1795 in Belfast to promote Protestant power in Northern Ireland, named for William of Orange (who became King William III of England and triumphed in Ireland at the head of a Protestant army at the Battle of the Boyne), of the German House of Nassau. His cousins and their descendants constitute the royal line of Holland.
The name is from the town of Orange on the Rhone in France, which became part of the Nassau principality in 1530. Its Roman name was Arausio, which is said in 19c. sources to be from aura "a breeze" and a reference to the north winds which rush down the valley, but perhaps this is folk etymology of a Celtic word. The name subsequently was corrupted to Auranche, then Orange.
The town has no obvious association with the fruit other than being on the road from Marseilles to Paris, along which masses of oranges were transported to northern France and beyond. In this roundabout way the political/religious movement of Northern Irish Protestantism acquired an association with the color orange, the Irish national flag acquired its orange band, and Syracuse University in New York state acquired its "Otto the Orange" mascot.
late 14c., oracioun, "a prayer," from Late Latin orationem (nominative oratio) "a speaking, speech, discourse; language, faculty of speech, mode of expressing; prayer," noun of action from past-participle stem of Latin ōrare "to pray to, plead, speak before an assembly" (see orator). The usual Old French form was oraison. Meaning "formal speech, discourse, eloquent or weighty address" is recorded from c. 1500.
"violent or tempestuous windstorm," late 15c. (Caxton), obsolete from 18c., from French orage "a storm," from Vulgar Latin *auraticum, from Latin aura "breeze, wind" (see aura (n.)). Related: Oragious.