"wrongful conduct, the doing of that which ought not to be done," especially "official misconduct, violation of a public trust or obligation," 1690s, from French malfaisance "wrongdoing," from malfaisant, from mal- "badly" (see mal-) + faisant, present participle of faire "to do," from Latin facere "to do" (from PIE root *dhe- "to set, put").
[S]pecifically, the doing of an act which is positively unlawful or wrongful, in contradistinction to misfeasance, or the doing of a lawful act in a wrongful manner. The term is often inappropriately used instead of misfeasance. [Century Dictionary]
Malfeasor "wrong-doer" is attested from early 14c. Related: Malfeasant.
formerly also empeach, late 14c., empechen, "to impede, hinder, prevent;" early 15c., "cause to be stuck, run (a ship) aground," also "prevent (from doing something)," from Anglo-French empecher, Old French empeechier "to hinder, stop, impede; capture, trap, ensnare" (12c., Modern French empêcher), from Late Latin impedicare "to fetter, catch, entangle," from assimilated form of in- "into, in" (from PIE root *en "in") + Latin pedica "a shackle, fetter," from pes (genitive pedis) "foot" (from PIE root *ped- "foot").
In law, at first in a broad sense, "to accuse, bring charges against" from late 14c.; more specifically, of the king or the House of Commons, "to bring formal accusation of treason or other high crime against (someone)" from mid-15c. The sense of "accuse a public officer of misconduct" had emerged from this by 1560s. The sense shift is perhaps via Medieval Latin confusion of impedicare with Latin impetere "attack, accuse" (see impetus), which is from the Latin verb petere "aim for, rush at" (from PIE root *pet- "to rush, to fly").
The Middle English verb apechen, probably from an Anglo-French variant of the source of impeach, was used from early 14c. in the sense "to accuse (someone), to charge (someone with an offense)." Related: Impeached; impeaching.
early 14c., "one who holds an official post, one entrusted with a responsibility or share of the management of some undertaking" (originally a high office), from Old French oficier "officer, official" (early 14c., Modern French officier), from Medieval Latin officiarius "an officer," from Latin officium "a service, a duty" (see office).
In Middle English also "a servant, a retainer of a great household; an official at court" (late 14c.). From late 14c. as "a military retainer," but the modern military sense of "one who holds a commission in the army or navy" is from 1560s. Applied to petty officials of justice from 16c.; U.S. use in reference to policemen is from 1880s.
The phrase officer and a gentleman in reference to one having the qualities of both is by 1762 and was standard language in British court-martial indictments ("behaviour infamous and scandalous such as is unbecoming the character of an officer and a gentleman").
The words 'officer and gentleman,' though in general to be understood as one single and indivisible term, appear not to be so used here. The misbehaviour, entailing on it the penalty declared by this article, must be such, as I understand it, as to implicate, in the first place, the officer; that is, it must arise in some sort out of his office; and affect incidentally only, the character of the gentleman. It must be such a misconduct, as must necessarily dissever what should ever be indivisible, the consideration of the officer from the gentleman. It must be of that decisively low, humiliating, and debasing kind, as to lay prostrate the honour of the gentleman, in the degradation of the officer. [Capt. Hough and George Long, "The Practice of Courts-Martial," London, 1825]
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