An oration is a speech delivered in a formal and dignified manner. A skilled public speaker is known as an orator. The art of delivering speeches is called oratory.
In classical rhetoric, notes George A. Kennedy, orations were classified "into a number of formal genres, each with a technical name and certain conventions of structure and content" (Classical Rhetoric and Its Christian and Secular Tradition, 1999). The primary categories of orations in classical rhetoric were deliberative (or political), judicial (or forensic), and epideictic (or ceremonial).
The term oration sometimes carries a negative connotation: "any impassioned, pompous, or long-winded speech" (Oxford English Dictionary).
From the Latin, "plead, speak, pray"
Clark Mills Brink
"What, then, is an oration? An oration is an oral discourse on a worthy and dignified theme, adapted to the average hearer, and whose aim is to influence the will of that hearer."
"It is a thing of no great difficulty to raise objections against another man's oration, nay, it is a very easy matter; but to produce a better in its place is a work extremely troublesome."
Paul Oskar Kristeller
"In classical antiquity, the oration was the very center of rhetorical theory and practice, though among the three types of speech-deliberative, judiciary, and epideictic-the last was to become the most important in the later centuries of antiquity. During the Middle Ages, the secular public speech and the political and social institutions supporting it disappeared more or less completely."
Rhetorica Ad Herennium, c. 90 BC
"The Introduction is the beginning of the discourse, and by it the hearer's mind is prepared for attention. The Narration or Statement of Facts sets forth the events that have occurred or might have occurred. By means of the Division we make clear what matters are agreed upon and what are contested, and announce what points we intend to take up. Proof is the presentation of our arguments, together with their corroboration. Refutation is the destruction of our adversaries' arguments. The Conclusion is the end of the discourse, formed in accordance with the principles of the Art."
David Rosenwasser and Jill Stephen
"If you read or listen to (for example) political speeches, you will find that many of them follow this order. This is because the form of the classical oration is suited primarily to argument-to the kind of writing in which the writer makes a case for or against something and refutes opposing arguments."
Don Paul Abbott
"Throughout the Renaissance, the oration remained fixed as the supreme form of discourse, just as it had been for the Romans. In the opinion of Walter Ong, the oration 'tyrannized over ideas of what expression as such-literary or other-was.'…
"It is no exaggeration to say that the rules of the classical oration were applied to every kind of discourse.