From 1640s as "mixed speech, pigin;" 1650s as "phraseology peculiar to a sect or profession," hence "mode of speech full of unfamiliar terms." Middle English also had it as a verb, jargounen "to chatter" (late 14c.), from French.
"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]
"conference, conversation, speech," especially with an enemy, mid-15c., parlai, from Old French parlée, from fem. past participle of Old French parler "to speak" (11c.), from Vulgar Latin *paraulare, from Late Latin parabolare "to speak (in parables)," from parabola "speech, discourse," from Latin parabola "comparison" (see parable).