1590s, "open assembly place, chief public square and marketplace of a town; popular political assembly held in such a place," from Greek agora "an assembly of the People" (as opposed to a council of Chiefs); "the place of assembly; a marketplace" (the typical spot for such an assembly), from ageirein "to assemble," from PIE root *ger- "to gather." The Greek word also could mean "public speaking," and "things to be sold." For sense, compare Roman forum.
"figurative treatment of an unmentioned subject under the guise of another similar to it in some way," late 14c., from Old French allegorie (12c.), from Latin allegoria, from Greek allegoria "figurative language, description of one thing under the image of another," literally "a speaking about something else," from allos "another, different" (from PIE root *al- (1) "beyond") + agoreuein "speak openly, speak in the assembly," from agora "assembly" (see agora). Related: Allegorist.
"eulogy, laudation, praise bestowed upon some person, action, or character," c. 1600, from French panégyrique (1510s), from Latin panegyricus "public eulogy," originally an adjective, "for a public festival," from Greek panēgyrikos (logos) "(a speech) given in or addressed to a public assembly," from panēgyris "public assembly (especially in honor of a god)," from pan- "all" (see pan-) + agyris "place of assembly," Aeolic form of agora (see agora). Related: Panegyrical; panegyrist.
"medicine that soothes pain," 1704, from adjective (1680s) "assuaging pain, soothing," from Late Latin paregoricus, from Greek paregorikos "soothing, encouraging, consoling," from paregorein "speak soothingly to," from paregoros "consoling," from para- "beside" (see para- (1)) + root of agoreuein "speak in public," from agora "public assembly," from PIE root *ger- "to gather."
1580s, in Aristotle's logic, "a highest notion," from French catégorie, from Late Latin categoria, from Greek kategoria "accusation, prediction, category," verbal noun from kategorein "to speak against; to accuse, assert, predicate," from kata "down to" (or perhaps "against;" see cata-) + agoreuein "to harangue, to declaim (in the assembly)," from agora "public assembly" (from PIE root *ger- "to gather").
The verb's original sense of "accuse" had weakened to "assert, name" by the time Aristotle applied kategoria to his 10 classes of things that can be named. Exactly what he meant by it "has been disputed almost from his own day till the present" [OED]. Sense of "any very wide and distinctive class, any comprehensive class of persons or things" is from 1660s.
category should be used by no-one who is not prepared to state (1) that he does not mean class, & (2) that he knows the difference between the two .... [Fowler]
"fantastic series or medley of illusive or terrifying figures or images," 1802, the name of a magic lantern exhibition brought to London in 1802 by Parisian showman Paul de Philipstal. The name is an alteration of French phantasmagorie, which is said to have been coined 1801 by French dramatist Louis-Sébastien Mercier as though to mean "crowd of phantoms," from Greek phantasma "image, phantom, apparition" (from PIE root *bha- (1) "to shine").
The second element appears to be a French form of Greek agora "assembly. "But the inventor of the word prob. only wanted a mouth-filling and startling term, and may have fixed on -agoria without any reference to the Greek lexicon" [OED]. The transferred meaning "shifting scene of many elements" is attested from 1822. Related: Phantasmagorical.
In Philipstal's 'phantasmagoria' the figures were made rapidly to increase and decrease in size, to advance and retreat, dissolve, vanish, and pass into each other, in a manner then considered marvellous. [OED]
Old English specan, variant of sprecan "to speak, utter words; make a speech; hold discourse (with others)" (class V strong verb; past tense spræc, past participle sprecen), from Proto-Germanic *sprekanan (source also of Old Saxon sprecan, Old Frisian spreka, Middle Dutch spreken, Old High German sprehhan, German sprechen "to speak," Old Norse spraki "rumor, report"), from PIE root *spreg- (1) "to speak," perhaps identical with PIE root *spreg- (2) "to strew," on notion of speech as a "scattering" of words.
The -r- began to drop out in Late West Saxon and was gone by mid-12c., perhaps from influence of Danish spage "crackle," also used in a slang sense of "speak" (compare crack (v.) in slang senses having to do with speech, such as wisecrack, cracker, all it's cracked up to be). Elsewhere, rare variant forms without -r- are found in Middle Dutch (speken), Old High German (spehhan), dialectal German (spächten "speak").
Not the primary word for "to speak" in Old English (the "Beowulf" author prefers maþelian, from mæþel "assembly, council," from root of metan "to meet;" compare Greek agoreuo "to speak, explain," originally "speak in the assembly," from agora "assembly").
[The egomaniac, as opposed to the megalomaniac,] does not regard it as necessary to dream of himself as occupying some invented social position. He does not require the world or its appreciation to justify in his own eyes himself as the sole object of his own interest. He does not see the world at all. Other people simply do not exist for him. The whole 'non-Ego' appears in his consciousness merely as a vague shadow or a thin cloud. The idea does not even occur to him that he is something out of the common, that he is superior to other people, and for this reason either admired or hated ; he is alone in the world ; more than that, he alone is the world and everything else, men, animals, things are unimportant accessories, not worth thinking about. [Max Nordau, "Degeneration," English translation, 1895]
Nordau's book was much-read, debated, and cited at the time and the word was associated with him (e.g. The Agora, July 1895).
Walker's use aside, its infrequent print appearance before 1895 seems to have been largely in the side of medicine that dealt with psychological matters:
The most frequent, yet the most extraordinary of these perversions of temper, are seen in young females. It is a species of aberration of the intellect, but short of insanity, real enough, but exaggerated, fictitious, factitious, and real at the same time. It frequently has its origin in dyspepsia, hysteria, or other malady, and in emotion of various kinds, such as disappointment, vexation, &c. Its object is frequently to excite and to maintain a state of active sympathy and attention, for which there, is as it were, a perpetual, morbid, and jealous thirst. It was rather aptly designated, by the clever relative of one patient, an ego-mania. [Marshall Hall, M.D., "Practical Observations and Suggestions in Medicine," London, 1845]