late 14c., originally in grammar (in reference to nouns that do not name concrete things), from Latin abstractus "drawn away," past participle of abstrahere "to drag away, detach, pull away, divert," also used figuratively; from assimilated form of ab "off, away from" (see ab-) + trahere "to draw" (from PIE root *tragh- "to draw, drag, move;" see tract (n.1)).

The meaning in philosophy, "withdrawn or separated from material objects or practical matters" (opposed to concrete) is from mid-15c. That of "difficult to understand, abstruse" is from c. 1400.

In the fine arts, "characterized by lack of representational qualities" by 1914; it had been a term at least since 1847 for music without accompanying lyrics. Abstract expressionism as an American-based uninhibited approach to art exemplified by Jackson Pollock is from 1952, but the term itself had been used in the 1920s of Kandinsky and others.

Oswald Herzog, in an article on "Der Abstrakte Expressionismus" (Sturm, heft 50, 1919) gives us a statement which with equal felicity may be applied to the artistic attitude of the Dadaists. "Abstract Expressionism is perfect Expressionism," he writes. "It is pure creation. It casts spiritual processes into a corporeal mould. It does not borrow objects from the real world; it creates its own objects .... The abstract reveals the will of the artist; it becomes expression. ..." [William A. Drake, "The Life and Deeds of Dada," 1922]

Then, that art we have called "abstract" for want of any possible descriptive term, with which we have been patient, and, even, appreciative, getting high stimulation by the new Guggenheim "non-objective" Art Museum, is reflected in our examples of "surrealism," "dadaism," and what-not, to assert our acquaintance in every art, fine or other. [Report of the Art Reference Department of Pratt Institute Free Library for year ending June 30, 1937]

Old English deaþ "total cessation of life, act or fact of dying, state of being dead; cause of death," in plural, "ghosts," from Proto-Germanic *dauthuz (source also of Old Saxon doth, Old Frisian dath, Dutch dood, Old High German tod, German Tod, Old Norse dauði, Danish død, Swedish död, Gothic dauus "death"), from verbal stem *dau-, which is perhaps from PIE root *dheu- (3) "to die" (see die (v.)). With Proto-Germanic *-thuz suffix indicating "act, process, condition."

I would not that death should take me asleep. I would not have him meerly seise me, and onely declare me to be dead, but win me, and overcome me. When I must shipwrack, I would do it in a sea, where mine impotencie might have some excuse; not in a sullen weedy lake, where I could not have so much as exercise for my swimming. [John Donne, letter to Sir Henry Goodere, Sept. 1608]

Of inanimate things, "cessation, end," late 14c. From late 12c. as "death personified, a skeleton as the figure of mortality." As "a plague, a great mortality," late 14c. (in reference to the first outbreak of bubonic plague; compare Black Death). Death's-head, a symbol of mortality, is from 1590s. Death's door "the near approach of death" is from 1540s.

As a verbal intensifier "to death, mortally" (as in hate (something) to death) 1610s; earlier to dead (early 14c.). Slang be death on "be very good at" is from 1839. To be the death of "be the cause or occasion of death" is in Shakespeare (1596). Expression a fate worse than death is from 1810 though the idea is ancient.

Death row "part of a prison exclusively for those condemned to capital execution" is by 1912. Death knell is attested from 1814; death penalty "capital punishment" is from 1844; death rate from 1859. Death-throes "struggle which in some cases accompanies death" is from c. 1300.

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

mid-14c., "generous," also "nobly born, noble, free;" from late 14c. as "selfless, magnanimous, admirable;" from early 15c. in a bad sense, "extravagant, unrestrained," from Old French liberal "befitting free people; noble, generous; willing, zealous" (12c.), and directly from Latin liberalis "noble, gracious, munificent, generous," literally "of freedom, pertaining to or befitting a free person," from liber "free, unrestricted, unimpeded; unbridled, unchecked, licentious."

This is conjectured to be from PIE *leudh-ero-, which probably originally meant "belonging to the people," though the precise semantic development is obscure; but compare frank (adj.). This was a suffixed form of the base *leudh- (2) "people" (source also of Old Church Slavonic ljudu, Lithuanian liaudis, Old English leod, German Leute "nation, people;" Old High German liut "person, people").

Who hath indeed, most like a liberal villain,

Confess'd the vile encounters they have had

A thousand times in secret.

["Much Ado," IV.1.93]

Liberal was used 16c.-17c. as a term of reproach with the meaning "free from restraint in speech or action." The Enlightenment revived it in a positive sense "free from prejudice, tolerant, not bigoted or narrow," which emerged 1776-88. In 19c. often theological rather than political, opposed to orthodox, used of Unitarians, Universalists, etc. For educational use, see liberal arts.

Purely in reference to political opinion, "tending in favor of freedom and democracy," it dates from c. 1801, from French libéral. In English the label at first was applied by opponents (often in the French form and with suggestions of foreign lawlessness) to the party more favorable to individual political freedoms. But also (especially in U.S. politics) tending to mean "favorable to government action to effect social change," which seems at times to draw more from the religious sense of "free from prejudice in favor of traditional opinions and established institutions" (and thus open to new ideas and plans of reform), which dates from 1823.

This is the attitude of mind which has come to be known as liberal. It implies vigorous convictions, tolerance for the opinions of others, and a persistent desire for sound progress. It is a method of approach which has played a notable and constructive part in our history, and which merits a thorough trial today in the attack on our absorbingly interesting American task. [Guy Emerson, "The New Frontier," 1920]

Proto-Indo-European root forming prepositions, etc., meaning "forward," and, by extension, "in front of, before, first, chief, toward, near, against," etc.

It forms all or part of: afford; approach; appropriate; approve; approximate; barbican; before; deprive; expropriate; far; first; for; for-; fore; fore-; forefather; foremost; former (adj.); forth; frame; frau; fret; Freya; fro; froward; from; furnish; furniture; further; galore; hysteron-proteron; impervious; improbity; impromptu; improve; palfrey; par (prep.); para- (1) "alongside, beyond; altered; contrary; irregular, abnormal;" paradise; pardon; paramount; paramour; parvenu; pellucid; per; per-; percent; percussion; perennial; perestroika; perfect; perfidy; perform; perfume; perfunctory; perhaps; peri-; perish; perjury; permanent; permeate; permit; pernicious; perpendicular; perpetual; perplex; persecute; persevere; perspective; perspire; persuasion; pertain; peruse; pervade; pervert; pierce; portray; postprandial; prae-; Prakrit; pre-; premier; presbyter; Presbyterian; preterite; pride; priest; primal; primary; primate; primavera; prime; primeval; primitive; primo; primogenitor; primogeniture; primordial; primus; prince; principal; principle; prior; pristine; private; privilege; privy; pro (n.2) "a consideration or argument in favor;" pro-; probably; probe; probity; problem; proceed; proclaim; prodigal; produce; profane; profess; profile; profit; profound; profuse; project; promise; prompt; prone; proof; proper; property; propinquity; prophet; prose; prostate; prosthesis; protagonist; Protean; protect; protein; Proterozoic; protest; proto-; protocol; proton; protoplasm; Protozoa; proud; prove; proverb; provide; provoke; prow; prowess; proximate; Purana; purchase; purdah; reciprocal; rapprochement; reproach; reprove; veneer.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pari "around, about, through," parah "farther, remote, ulterior," pura "formerly, before," pra- "before, forward, forth;" Avestan pairi- "around," paro "before;" Hittite para "outside of," Greek peri "around, about, near, beyond," pera "across, beyond," paros "before," para "from beside, beyond," pro "before;" Latin pro "before, for, on behalf of, instead of," porro "forward," prae "before," per "through;" Old Church Slavonic pra-dedu "great-grandfather;" Russian pere- "through;" Lithuanian per "through;" Old Irish ire "farther," roar "enough;" Gothic faura "before," Old English fore (prep.) "before, in front of," (adv.) "before, previously," fram "forward, from," feor "to a great distance, long ago;" German vor "before, in front of;" Old Irish air- Gothic fair-, German ver-, Old English fer-, intensive prefixes.

Middle English kēpen, from late Old English cepan (past tense cepte) "to seize, hold; seek after, desire," also "to observe or carry out in practice; look out for, regard, pay attention to," from Proto-Germanic *kopjan, which is of uncertain origin. Old English cepan was used c. 1000 to render Latin observare, so perhaps it is related to Old English capian "to look" (from Proto-Germanic *kap-), which would make the basic sense "to keep an eye on, see to it."

The word prob. belonged primarily to the vulgar and non-literary stratum of the language; but it comes up suddenly into literary use c. 1000, and that in many senses, indicating considerable previous development. [OED]

The senses exploded in Middle English: "to guard, defend" (12c.); "restrain (someone) from doing something" (early 13c.); "take care of, look after; protect or preserve (someone or something) from harm, damage, etc." (mid-13c.); "preserve, maintain, carry on" a shop, store, etc. (mid-14c.); "prevent from entering or leaving, force to remain or stay" (late 14c.); "preserve (something) without loss or change," also "not divulge" a secret, private information, etc., also "to last without spoiling" (late 14c.); "continue on" (a course, road, etc.), "adhere to" a course of action (late 14c.); "stay or remain" (early 15c.); "to continue" (doing something) (mid-15c.). It is used to translate both Latin conservare "preserve, keep safe" and tenere "to keep, retain."

From 1540s as "maintain for ready use;" 1706 as "have habitually in stock for sale." Meaning "financially support and privately control" (usually in reference to mistresses) is from 1540s; meaning "maintain in proper order" (of books, accounts) is from 1550s.

To keep at "work persistently" is from 1825; to keep on "continue, persist" is from 1580s. To keep up is from 1630s as "continue alongside, proceed in pace with," 1660s as "maintain in good order or condition, retain, preserve," 1680s as "support, hold in an existing state." To keep it up "continue (something) vigorously" is from 1752. To keep to "restrict (oneself) to" is from 1711. To keep off (trans.) "hinder from approach or attack" is from 1540s; to keep out (trans.) "prevent from entering" is from early 15c.

mid-14c., "state or fact of knowing; what is known, knowledge (of something) acquired by study; information;" also "assurance of knowledge, certitude, certainty," from Old French science "knowledge, learning, application; corpus of human knowledge" (12c.), from Latin scientia "knowledge, a knowing; expertness," from sciens (genitive scientis) "intelligent, skilled," present participle of scire "to know."

The original notion in the Latin verb probably is "to separate one thing from another, to distinguish," or else "to incise." This is related to scindere "to cut, divide" (from PIE root *skei- "to cut, split;" source also of Greek skhizein "to split, rend, cleave," Gothic skaidan, Old English sceadan "to divide, separate").

OED writes that the oldest English sense of the word now is restricted to theology and philosophy. From late 14c. in English as "book-learning," also "a particular branch of knowledge or of learning, systematized knowledge regarding a particular group of objects;" also "skillfulness, cleverness; craftiness." From c. 1400 as "experiential knowledge;" also "a skill resulting from training, handicraft; a trade."

From late 14c. in the more specific sense of "collective human knowledge," especially that gained by systematic observation, experiment, and reasoning. The modern (restricted) sense of "body of regular or methodical observations or propositions concerning a particular subject or speculation" is attested by 1725; in 17c.-18c. this commonly was philosophy.

The sense of "non-arts studies" is attested from 1670s. The distinction is commonly understood as between theoretical truth (Greek epistemē) and methods for effecting practical results (tekhnē), but science sometimes is used for practical applications and art for applications of skill.

The predominant modern use, "natural and physical science," generally restricted to study of the phenomena of the material universe and its laws, is by mid-19c.

The men who founded modern science had two merits which are not necessarily found together: Immense patience in observation, and great boldness in framing hypotheses. The second of these merits had belonged to the earliest Greek philosophers; the first existed, to a considerable degree, in the later astronomers of antiquity. But no one among the ancients, except perhaps Aristarchus, possessed both merits, and no one in the Middle Ages possessed either. [Bertrand Russell, "A History of Western Philosophy," 1945] 

Science, since people must do it, is a socially embedded activity. It progresses by hunch, vision, and intuition. Much of its change through time does not record a closer approach to absolute truth, but the alteration of cultural contexts that influence it so strongly. Facts are not pure and unsullied bits of information; culture also influences what we see and how we see it. Theories, moreover, are not inexorable inductions from facts. The most creative theories are often imaginative visions imposed upon facts; the source of imagination is also strongly cultural. [Stephen Jay Gould, introduction to "The Mismeasure of Man," 1981]