irony (n.)

mid-14c., "fluid or juice of an animal or plant," from Old North French humour "liquid, dampness; (medical) humor" (Old French humor, umor; Modern French humeur), from Latin umor "body fluid" (also humor, by false association with humus "earth"); related to umere "be wet, moist," and to uvescere "become wet" (see humid).

In old medicine, "any of the four body fluids" (blood, phlegm, choler, and melancholy or black bile).

The human body had four humors—blood, phlegm, yellow bile, and black bile—which, in turn, were associated with particular organs. Blood came from the heart, phlegm from the brain, yellow bile from the liver, and black bile from the spleen. Galen and Avicenna attributed certain elemental qualities to each humor. Blood was hot and moist, like air; phlegm was cold and moist, like water; yellow bile was hot and dry, like fire; and black bile was cold and dry, like earth. In effect, the human body was a microcosm of the larger world. [Robert S. Gottfried, "The Black Death," 1983]

 Their relative proportions were thought to determine physical condition and state of mind. This gave humor an extended sense of "mood, temporary state of mind" (recorded from 1520s); the sense of "amusing quality, funniness, jocular turn of mind" is first recorded 1680s, probably via sense of "whim, caprice" as determined by state of mind (1560s), which also produced the verb sense of "indulge (someone's) fancy or disposition." Modern French has them as doublets: humeur "disposition, mood, whim;" humour "humor." "The pronunciation of the initial h is only of recent date, and is sometimes omitted ..." [OED].

For aid in distinguishing the various devices that tend to be grouped under "humor," this guide, from Henry W. Fowler ["Modern English Usage," 1926] may be of use:

HUMOR: motive/aim: discovery; province: human nature; method/means: observation; audience: the sympathetic

WIT: motive/aim: throwing light; province: words & ideas; method/means: surprise; audience: the intelligent

SATIRE: motive/aim: amendment; province: morals & manners; method/means: accentuation; audience: the self-satisfied

SARCASM: motive/aim: inflicting pain; province: faults & foibles; method/means: inversion; audience: victim & bystander

INVECTIVE: motive/aim: discredit; province: misconduct; method/means: direct statement; audience: the public

IRONY: motive/aim: exclusiveness; province: statement of facts; method/means: mystification; audience: an inner circle

CYNICISM: motive/aim: self-justification; province: morals; method/means: exposure of nakedness; audience: the respectable

SARDONIC: motive/aim: self-relief; province: adversity; method/means: pessimism; audience: the self

Middle English iron, iren, yron, from Old English iren, variant (with rhotacism of -s-) of isen, later form of isern, isærn "the metal iron; an iron weapon or instrument," from Proto-Germanic *isarn (source also of Old Saxon isarn, Old Frisian isern, Old Norse isarn, Middle Dutch iser, Old High German isarn, German Eisen).

This perhaps is an early borrowing of Celtic *isarnon (compare Old Irish iarn, Welsh haiarn), which Watkins suggests is from PIE *is-(e)ro- "powerful, holy," from PIE *eis "strong" (source also of Sanskrit isirah "vigorous, strong," Greek ieros "strong"), on the notion of "holy metal" or "strong metal" (in contrast to softer bronze).

Both an adjective and a noun in Old English, but in form an adjective. The alternative isen survived into early Middle English as izen. In southern England the Middle English word tended to be ire, yre, with loss of -n, perhaps regarded as an inflection; in the north and Scotland, however, the word tended to be contracted to irn, yrn, still detectable in dialect.

Right so as whil that Iren is hoot men sholden smyte. [Chaucer, c. 1386]

Chemical symbol Fe is from the Latin word for the metal, ferrum (see ferro-).

The meaning "metal device used to press or smooth clothes" is from 1610s. The meaning "golf club with an iron head" is by 1842. To have (too) many irons in the fire "to be doing too much at once" is from 1540s. Iron lung "artificial respiration tank" is from 1932. The iron crown was that of the ancient kings of Lombardy, with a thin band of iron in the gold, said to have been forged from a nail of Christ's Cross.

Iron horse "railroad locomotive" is from an 1839 poem. Iron maiden, instrument of torture, is from 1837 (probably translating German eiserne jungfrau). The unidentified French political prisoner known as the man in the iron mask died in the Bastille in 1703. In British history, Wellington was called the Iron Duke by 1832.