ape (n.)
Old English apa (fem. ape) "an ape, a monkey," from Proto-Germanic *apan (source also of Old Saxon apo, Old Norse api, Dutch aap, German affe), probably a borrowed word, perhaps from Celtic (compare Old Irish apa, Welsh epa) or Slavic (compare Old Bohemian op, Slovak opitza), and the whole group probably is ultimately from an Eastern or non-Indo-European language.

The common word until the emergence of monkey in 16c. More technically, in zoology, "a simian; tail-less, man-like monkey" 1690s. The only native apes in Europe are the Barbary apes of Gibraltar, intelligent and docile, and these were the showman's apes of the Middle Ages. Apes were noted in medieval times for mimicry of human action, hence, perhaps, the other figurative use of the word, to mean "a fool" (c. 1300). To go ape (in emphatic form, go apeshit) "go crazy" is 1955, U.S. slang, said to be from the armed forces. To lead apes in hell (1570s) was the fancied fate of one who died an old maid. Middle English plural was occasionally apen. Middle English also had ape-ware "deceptions, tricks."
ape (v.)
"to imitate," 1630s, but the notion is implied earlier, as in the phrase play the ape (1570s), and Middle English apeshipe "ape-like behavior, simulation" (mid-15c.); and the noun sense of "one who mimics" may date from early 13c. Related: Aped; aping.
ape-man (n.)
also apeman, hypothetical "missing link" between the highest anthropoid apes and human beings, progenitor of the human race, 1879, in a translation of Haeckel, from ape (n.) + man (n.). Man-ape is attested from 1878. The name Martin Halfape appears in an English roll from 1227.
Apennine
Latin Apenninus (mons), the chain of mountains which forms the spine of Italy, perhaps from Celtic penn "hill, head of land" (see pen-).
apercu (n.)
"quick impression, hasty glance, sketch, brief survey," 1821 as a French word in English, from French aperçu (18c. in this sense), noun use of past participle of apercevoir "to perceive" (11c.), from Gallo-Roman *adpercipere, from Latin ad "to" (see ad-) + percipere "to perceive" (see perceive).
aperiodic (adj.)
"without periodicity," 1874, from a- (3) "not" + periodic.
aperitif (n.)
"alcoholic drink taken before a meal to stimulate the appetite," 1890, from French apéritif "laxative, laxative liqueur," literally "opening," from Latin aperitivus, from aperire "to open, uncover," from PIE compound *ap-wer-yo- from *ap- "off, away" (see apo-) + root *wer- (4) "to cover." A doublet of apertive.
apert (adj.)
"open, evident, undisguised," early 14c., from Old French apert "obvious, evident, visible, plain to see," and directly from Latin apertus "open, uncovered, unclosed," past participle of aperire "to open, uncover" (see overt). Related: Apertly.
apertive (n.)
"medicine capable of opening or dilating" (pores, bowels, etc.), "a laxative," early 15c., also as an adjective, from Latin aperitivus, from aperire "to open, uncover," from PIE compound *ap-wer-yo- from *ap- "off, away" (see apo-) + root *wer- (4) "to cover." Also aperient (1620s).
aperture (n.)
early 15c., "an opening, hole, orifice," from Latin apertura "an opening," from apertus, past participle of aperire "to open, uncover," from PIE compound *ap-wer-yo- from *ap- "off, away" (see apo-) + root *wer- (4) "to cover." In optics, diameter of the exposed part of a telescope, microscope, etc., 1660s.
apex (n.)
"the tip, point, or summit" of anything, c. 1600, from Latin apex "summit, peak, tip, top, extreme end;" probably related to apere "to fasten, fix," hence "the tip of anything" (one of the meanings in Latin was "small rod at the top of the flamen's cap"), from PIE *ap- (1) "to take, reach" (see apt). Proper plural is apices.
aphagia (n.)
"inability to swallow," 1854, from a- (3) "not, without" + abstract noun from Greek phagein "to eat" (from PIE root *bhag- "to share out, apportion; to get a share").
aphasia (n.)
in pathology, "loss of ability to speak," especially as result of brain injury or disorder, 1867, from Modern Latin aphasia, from Greek aphasia "speechlessness," abstract noun from a- "without" (see a- (3)) + phasis "utterance," from phanai "to speak," related to pheme "voice, report, rumor" from PIE root *bha- (2) "to speak, tell, say").
APHASIA is the term which has recently been given to the loss of the faculty of articulate language, the organs of phonation and of articulation, as well as the intelligence, being unimpaired. The pathology of this affection is at the present time the subject of much discussion in the scientific world; the French Academy devoted several of their séances during the year 1865 to its special elucidation, and the Medical Journals of France and of our own country have lately contained a good deal of original matter bearing upon this obscure feature in cerebral pathology. [Frederic Bateman, M.D., "Aphasia," London, 1868]
aphasic (adj.)
"characterized by pathological loss of ability to speak," 1867, from aphasia + -ic. Aphasiac (1868) is better as the noun, "one suffering from aphasia," but both words have been used in both senses.
aphelion (n.)
"point farthest from the sun" (of a celestial body's orbit), 1670s, a Grecianized form of Modern Latin aphelium (itself attested in English from 1650s), coined by Johannes Kepler based on Greek apo heliou "away from the sun," from assimilated form of apo "away from" (see apo-) + heliou, genitive of helios "sun" (from PIE root *sawel- "the sun"). Formed on the model of Ptolemaic apogaeum (see apogee) to reflect the new heliocentric model of the universe.
apheresis (n.)
also aphaeresis, "suppression of a letter or syllable at the beginning of a word," 1610s, from Latin aphaeresis, a grammarians' use of Greek aphairesis "a taking away," from aphairein "to take away," from assimilated form of apo "from, off" (see apo-) + hairein "to take" (see heresy). Related: Apheretic.
aphetic (adj.)
1880, "suggested by the Editor" (OED editor Sir James A.H. Murray (1837-1915)) for "gradual and unintentional loss of a short unaccented vowel at the beginning of a word" [OED], as squire from esquire, venture from adventure. With -ic + aphesis (1880), from Greek aphienai "to let go, to send forth," from assimilated form of apo "from" (see apo-) + hienai "to send, throw" (from PIE root *ye- "to throw, impel"). Compare apheresis.
aphid (n.)
1849, Englished from Modern Latin aphides, plural of aphis, coined by Linnaeus (1758), though where he got it and why he applied it to the plant louse are mysteries. The theory favored by OED as "least improbable" is that it derives from the plural of Greek apheides "unsparing, lavishly bestowed," in reference either to the "prodigious rate of production" of the insects or their voracity. The colloquial name was ant-cow (1847). Related: Aphidian (1855).
aphonia (n.)
in pathology, "want of voice, loss of voice through some physical condition," 1778, from medical Latin aphonia, from Greek aphonia "speechlessness," abstract noun from aphonos "voiceless," from a- "not, without" (see a- (3)) + phone "voice," from PIE root *bha- (2) "to speak, tell, say" + abstract noun ending (see -ia). Englished form aphony is attested from 1680s.
aphonic (adj.)
"having no sound," 1827, with -ic + Greek aphonos "voiceless," from a- "not, without" (see a- (3)) + phone "voice," from PIE root *bha- (2) "to speak, tell, say."
aphorism (n.)
1520s, "concise statement of a principle" (especially in reference to the "Aphorisms of Hippocrates"), from Middle French aphorisme (corrected from Old French aufforisme, 14c.), from Late Latin aphorismus, from Greek aphorismos "definition; short, pithy sentence," from aphorizein "to mark off, divide," from apo "from" (see apo-) + horizein "to bound" (see horizon).

General sense of "short, pithy statement containing a truth of general import" (e.g. "life is short, and art is long") is from 1580s in English. Distinguished from an axiom, which is a statement of self-evident truth; an epigram is like an aphorism, but lacking in general import. Maxim and saying can be used as synonyms for aphorism, but maxims tend to be practical and sayings tend to be more commonplace and have an author's name attached.
aphoristic (adj.)
"of the nature of an aphorism," 1753, from Latinized form of Greek aphoristikos, from aphorismos "definition, pithy sentence" (see aphorism). Related: Aphoristically (1650s). Aphorismic "having the form of an aphorism" is from 1794.
aphotic (adj.)
"untouched by sunlight, lightless" (in reference to deep-sea regions), 1903, Modern Latin, from Greek a- "not, without" (see a- (3)) + phos (genitive photos) "light" (from PIE root *bha- (1) "to shine") + -ic. Aphotic zone is recorded from 1913.
Aphra
fem. proper name, apparently from a misunderstanding of Hebrew bebheth 'Aphrah "in the house of Aphrah" (Micah i.10), in which Aphrah probably is the name of a town, not a person. [Klein]
aphrodisiac (n.)
"preparation or drug which excites sexual desire," 1719, from Latinized form of Greek aphrodisiakos "inducing sexual desire," from Aphrodisios, "sacred to Aphrodite, pertaining to Aphrodite," Greek goddess of love and beauty (see Aphrodite), whose name also meant "sexual pleasure; a temple of Aphrodite." As an adjective from 1775 (earlier was aphrodisical, 1719). Aphrodisian "devoted to sexual love" is attested from 1864.
Aphrodite (n.)
Greek goddess of love and beauty, personification of female grace, 1650s; the ancients derived her name from Greek aphros "foam," from the story of her birth, but the word is perhaps rather from Phoenician Ashtaroth (Assyrian Ishtar). Beekes writes, "As the goddess seems to be of oriental origin ..., the name probably comes from the East too. .... It may have entered Greek via another language." He concludes, "[I]t seems possible that the name came from the one languages [sic] which on historical grounds we should expect to be relevant: Cypriot Phoenician."

Associated by the Romans with their Venus, originally a less-important goddess. In 17c. English, pronounced to rhyme with night, right, etc.
apiarist (n.)
"bee-keeper, bee-master," 1816; see apiary + -ist.
apiary (n.)
1650s, from Latin apiarium "bee-house, beehive," noun use of neuter of apiarius "of bees," from apis "bee," a mystery word unrelated to any similar words in other Indo-European languages. A borrowing from Semitic has been proposed. Related: Apiarian.
apical (adj.)
"of or belonging to an apex," 1827, from Latin apicem, from apex (see apex) + -al (1).
apiculture (n.)
"the rearing of bees," 1859, from Latin apis "bee" (see apiary) on analogy of agriculture, etc. (see culture (n.)).
apiece (adv.)
"for each" (thing, person, etc.), 1550s, a contraction of a pece (mid-15c.), originally of coins, objects for sale, etc. (see a (2) + piece (n.)).
aping (n.)
"imitation, mimicry," 1680s, verbal noun from ape (v.). Apery in the same sense is attested from 1610s.
apish (adj.)
"inclined to imitate servilely," 1530s; "looking like an ape," 1560s; from ape (n.) + -ish. Related: Apishly; apishness.
aplasia (n.)
"defective or arrested development of a body part," 1876, medical Latin, from Greek a- "not, without" (see a- (3)) + -plasia. Related: Aplastic.
aplenty (adj.)
also a-plenty, 1830, originally U.S. colloquial, from a- (1) + plenty (n.). First attested in writings of J. Fenimore Cooper.
aplomb (n.)
"assurance springing from confidence in oneself," 1828, from French aplomb "self-possession," literally "perpendicularity" (16c.), from phrase à plomb "poised upright, balanced," literally "on the plumb line," from Latin plumbum "(the metal) lead" (see plumb (n.)), of which the weight at the end of the line was made.
The staple figure in novels is the man of aplomb, who sits, among the young aspirants and desperates, quite sure and compact, and, never sharing their affections or debilities, hurls his word like a bullet when occasion requires, knows his way, and carries his points. They may scream or applaud, he is never engaged or heated. Napoleon is the type of this class in modern history ; Byron's heroes in poetry. [Emerson, "Social Aims," 1875]
apnea (n.)
in pathology, "suspension of breathing," originally, and until recently most commonly, apnoea, 1719, Modern Latin, from Greek apnoia "absence of respiration," from apnoos "without breathing, without wind," from a- "not, without" (see a- (3)) + pnein "to breathe" (see pneuma).
apnoeic (adj.)
1883, from apnoea (see apnea) + -ic.
apo koinu
Greek, literally "in common." Applied to sentences with one subject and two predicates; a formation rare in modern English, though it occurs more often in Old English. Compare koine.
apo-
before vowels ap-, word-forming element meaning "of, from, away from; separate, apart from, free from," from Greek apo "from, away from; after; in descent from," in compounds, "asunder, off; finishing, completing; back again," of time, "after," of origin, "sprung from, descended from; because of," from PIE root *apo- "off, away" (source also of Sanskrit apa "away from," Avestan apa "away from," Latin ab "away from, from," Gothic af, Old English of "away from," Modern English of, off).
apocalypse (n.)
late 14c., "revelation, disclosure," from Church Latin apocalypsis "revelation," from Greek apokalyptein "uncover, disclose, reveal," from apo "off, away from" (see apo-) + kalyptein "to cover, conceal," from PIE root *kel- (1) "to cover, conceal, save." The Christian end-of-the-world story is part of the revelation in John of Patmos' book "Apokalypsis" (a title rendered into English as pocalipsis c. 1050, "Apocalypse" c. 1230, and "Revelations" by Wyclif c. 1380).

Its general sense in Middle English was "insight, vision; hallucination." The meaning "a cataclysmic event" is modern (not in OED 2nd ed., 1989); apocalypticism "belief in an imminent end of the present world" is from 1858. As agent nouns, "author or interpreter of the 'Apocalypse,'" apocalypst (1829), apocalypt (1834), and apocalyptist (1824) have been tried.
apocalyptic (adj.)
1660s, "pertaining to the 'Revelation of St. John' in the New Testament," from Greek apokalyptikos, from apokalyptein "uncover, disclose, reveal" (see apocalypse). The original general sense was "prophetic" (1680s); meaning "pertaining to the imminent end of the world" is attested by 1864. Related: Apocalyptical (1630s).
apocrypha (n.)
late 14c., Apocrifa, in reference to the apocryphal books of the Bible, from Late Latin apocrypha (scripta), from neuter plural of apocryphus "secret, not approved for public reading," from Greek apokryphos "hidden; obscure, hard to understand," thus "(books) of unknown authorship" (especially those included in the Septuagint and Vulgate but not originally written in Hebrew and not counted as genuine by the Jews), from apo "off, away" (see apo-) + kryptein "to hide" (see crypt).

Non-Biblical sense "writing of doubtful authorship or authenticity" is from 1735. Properly plural (the single would be Apocryphon or apocryphum), but commonly treated as a collective singular.
apocryphal (adj.)
1580s, "of doubtful authenticity," from apocrypha + -al (1). Middle English had apocrive (late 14c.) in same sense. Related: Apocryphally.
apodal (adj.)
"having no feet," 1769, with -al + Greek apous (genitive apodos) "footless," from a- "not, without" (see a- (3)) + pous "foot" (from PIE root *ped- "foot").
apodictic (adj.)
also apodeictic, "clearly demonstrated," 1650s, from Latin apodicticus, from Greek apodeiktikos, from apodeiktos, verbal adjective of apodeiknynai "to show off, demonstrate, show by argument, point out, prove," literally "to point away from" (other objects, at one), from apo "off, away" (see apo-) + deiknynai "to show" (from PIE root *deik- "to show"). Related: Apodictical (1630s); apodictically (1610s).
apodyterium (n.)
"undressing room" (in a Greek or Roman bath house or palaestra), 1690s, from Latin apodyterium, from Greek apodyterion "undressing room," from apodyein "to put off, undress," from apo "off" (see apo-) + dyein "to put on, enter, go in" (see ecdysiast).
apogee (n.)
"point at which the moon is farthest from the earth," 1590s, from French apogée or directly from Latin apogaeum, from Greek apogaion (diastema) "(distance) away from the earth," from apogaion, neuter adjective, "from land," here in a specialized sense "away from the earth," from apo "off, away" (see apo-) + gaia/ge "earth" (see Gaia).

Figurative sense "climax, culmination" is from 1640s. A term from Ptolemaic astronomy, which regarded the earth as the center of the universe and applied the word to the sun and planets; for these bodies it was displaced in the Copernican system by aphelion. Adjective forms are apogeal, apogean, apogeic.
apolitical (adj.)
1947, from a- (3) "not" + political.
Apollo
Olympian deity, god of music, poetry, medicine, etc., later identified with Helios, the sun god; the name is a Latin form of Greek Apollon, which is of uncertain origin. Beekes, after considering the alternatives, concludes, "In spite of repeated attempts, there is no IE etymology. ... The name is probably Pre-Greek, and Hitt. Appaliunaš, mentioned in a treaty between Alaksandus of Wilusa and the Hittite king, may well be the Pre-Greek proto-form Apal'un." The U.S. space program ran from 1961 to 1972.