The Collaborative International Dictionary
Hysterology \Hys`ter*ol"o*gy\, n. [Gr. ?; ? the latter + ? discourse: cf. F. hyst['e]rologie.] (Rhet.) A figure by which the ordinary course of thought is inverted in expression, and the last put first; -- called also hysteron proteron.
Douglas Harper's Etymology Dictionary
1560s, from Late Latin, from Greek, literally "the latter (put as) the former." A figure of speech in which what should come last is put first, from hysteron, neuter of hysteros "latter, second, after" (from PIE *ud-tero-, from root *ud- "up, out;" see out) + proteron, neuter of proteros "before, former," from PIE *pro-, from root *per- (1) "forward, through" (see per).
Wiktionary
n. 1 (context rhetoric English) A figure of speech in which a phrase that should come last is put first; hysterology. 2 An inversion or reversal of the natural order of things.
WordNet
n. reversal of normal order of two words or sentences etc. (as in `bred and born')
the logical fallacy of using as a true premise a proposition that is yet to be proved
Wikipedia
The hysteron proteron (from the , hýsteron próteron, "latter before") is a rhetorical device. It occurs when the first key word of the idea refers to something that happens temporally later than the second key word. The goal is to call attention to the more important idea by placing it first.
The standard example comes from the Aeneid of Virgil: "Moriamur, et in media arma ruamus" ("Let us die, and charge into the thick of the fight"; ii. 353). An example of hysteron proteron encountered in everyday life is the common reference to putting on one's "shoes and socks", rather than "socks and shoes".
By this deliberate reversal, hysteron proteron draws attention to the important point, so giving it primacy. Hysteron proteron is a form of hyperbaton, which describes general rearrangements of the sentence.
It can also be defined as a figure of speech consisting of the reversal of a natural or rational order (as in "then came the thunder and the lightning").
Usage examples of "hysteron proteron".
To each memorable image you attach a thought, a label, a category, a piece of the cosmic furniture, syllogisms, an enormous sorites, chains of apothegms, strings of hypallages, rosters of zeugmas, dances of hysteron proteron, apophantic logoi, hierarchic stoichea, processions of equinoxes and parallaxes, herbaria, genealogies of gymnosophists—.
To each memorable image you attach a thought, a label, a category, a piece of the cosmic furniture, syllogisms, an enormous sorites, chains of apothegms, strings of hypallages, rosters of zeugmas, dances of hysteron proteron, apophantic logoi, hierarchic stoichea, processions of equinoxes and parallaxes, herbaria, genealogies of gymnosophists- and so on, to infinity.