Online Etymology Dictionary

argosy (n.): 1570s, from Italian (nave) Ragusea "(vessel) of Ragusa," maritime city on the Dalmatian coast of the Adriatic (modern Dubrovnik in Croatia). Their large merchant ships brought rich Eastern goods to 16c. England. The city name sometimes was Aragouse or Arragosa in 16c. English.
argot (n.): 1860, from French argot (17c.) "the jargon of Paris rogues and thieves," earlier "the company of beggars," from Middle French argot, "group of beggars," origin unknown. Gamillscheg suggests a connection to Old French argoter "to cut off the stubs left in pruning," with a connecting sense of "to get a grip on." The best English equivalent is perhaps cant. The German equivalent is Rotwelsch, literally "Red Welsh," but the first element may be connected with Middle High German rot "beggar." Earlier in English was pedlar's French (1520s) "language of thieves and vagabonds."
arguable (adj.): 1610s, from argue + -able.
arguably (adv.): "as may be shown by argument," 1890, from arguable + -ly (2).
argue (v.): c.1300, "to make reasoned statements to prove or refute a proposition," from Old French arguer "maintain an opinion or view; harry, reproach, accuse, blame" (12c.), from Latin argutare "to prattle, prate," frequentative of arguere "make clear, make known, prove, declare, demonstrate," from PIE *argu-yo-, from root *arg- "to shine, be white, bright, clear" (see argent). Meaning "to oppose, dispute" is from late 14c. Related: Argued; arguing.
arguendo: "in the course of argument," 1817, courtroom Latin, from Medieval Latin ablative of arguendum, gerundive of arguere "to argue" (see argue).
arguer (n.): late 14c., agent noun from argue (v.).
argufy (v.): 1751, colloquial, from argue + -fy.
argument (n.): early 14c., "statements and reasoning in support of a proposition," from Old French arguement "reasoning, opinion; accusation, charge" (13c.), from Latin argumentum "evidence, ground, support, proof; a logical argument," from arguere "to argue" (see argue). Sense passed through "subject of contention" to "a quarrel," a sense formerly attached to argumentation.
argumentation (n.): mid-15c., "presentation of formal arguments," from Old French argumentacion (14c.), from Latin argumentationem (nominative argumentatio) "the bringing forth of a proof," noun of action from past participle stem of argumentari (see argue). Meaning "debate, wrangling, argument back and forth" is from 1530s.
argumentative (adj.): mid-15c., "pertaining to arguments," from Old French argumentatif or directly from Latin argumentat-, past participle stem of argumentari (see argue) + -ive. Meaning "fond of arguing" is recorded from 1660s. Related: Argumentatively; argumentativeness.
Argus: hundred-eyed giant of Greek mythology, late 14c., from Latin, from Greek Argos, literally "the bright one," from argos "shining, bright" (see argent). His epithet was Panoptes "all-eyes." After his death, Hera transferred his eyes to the peacock's tail. Used in figurative sense of "very vigilant person."
Argyle (n.): "diamond-shaped pattern of two or more colors in fabric," said to be so called from similarity to tartans worn by Campbell clan of Argyll, Scotland. The place name is literally "land of the Gaels," from Old Irish airer "country." Argyle socks is from 1935.
aria (n.): from Italian aria, literally "air" (see air (n.1)).
Arian (adj.): 1530s, pertaining to the doctrines of Arius, priest in Alexandria early 4c., who posed the question of Christ's nature in terms which appeared to debase the Savior's relation to God (denial of consubstantiation). Besides taking an abstract view of Christ's nature, he reaffirmed man's capacity for perfection. The dissention was widespread and split the Church for about a century during a crucial time.
Arianism (n.): c.1600, from Arian + -ism.
arid (adj.): 1650s, "dry, parched," from French aride (15c.) or directly from Latin aridus "dry, arid, parched," from arere "to be dry," from PIE root *as- "to burn, glow" (see ash (n.1)). Figurative sense of "uninteresting" is from 1827. Related: Aridly.
aridity (n.): 1590s, from Middle French aridité or directly from Latin ariditatem (nominative ariditas) "dryness," from aridus (see arid). The Latin word was used figuratively of unadorned styles as well as stingy men.
ariel: 1382, in the Wyclif Bible, a word taken untranslated from the Vulgate, from Greek ariel (Sept.), from Hebrew ariel; in later Bibles, translated as "altar."
(Gesenius would here translate "fire-hearth of God," after Arab. arr; elsewhere in O.T. the same word occurs as a man's name, and appellation of Jerusalem, where it is taken as = "lion of God.") Ariel in T. Heywood and Milton is the name of an angel, in Shakespeare of "an Ayrie spirit"; in Astron. of one of the satellites of Uranus. [OED]
As the name of a species of gazelle found in the Middle East, 1832, from Arabic aryil, variant of ayyil "stag."
Aries: zodiac constellation usually identified as "the Ram," late Old English, from Latin aires "ram" (cf. arietare "to butt"), from a PIE root meaning "spring, jump" (cf. Lithuanian erytis, Old Church Slavonic jarici, Armenian oroj "lamb;" Greek eriphos, Old Irish heirp "kid"). Meaning "person born under the sign of Aries" is from 1894; they also have been called Arian (1917).
aright (adv.): "in a correct way," Old English ariht, from a- (1) "of" + right (adj.).
aril (n.): "accessory covering of seeds," 1794, from Modern Latin arillus, from Medieval Latin arilli, Spanish arillos "dried grapes, raisins."
Arimasp (n.): Latin Arimaspi (plural), from Greek Arimaspoi, mythical race of one-eyed people in Northern Europe who battled griffins over gold the griffins guarded. The name is said to be Scythian for "one-eyed." Related: Arimaspian.
arioso: "melodious, in a melodious way," 1742, from Italian aria "melody" (see aria).
arise (v.): Old English arisan "to get up, rise; spring from, originate; spring up, ascend" (cognate with Old Saxon arisan, Gothic urreisan), from a- (1) "of" + rise (v.). Mostly replaced by rise except in reference to circumstances. Related: Arising; arose; arisen.
arisen: past participle of arise (q.v.).
arising (n.): verbal noun from arise (v.). Replaced in most senses by rising.
aristarchy (n.): "government by the best men," from Greek aristarkhia, from aristos "best" (see aristocracy) + -arkhia (see -archy).
aristocracy (n.): 1560s, from Middle French aristocracie (Modern French aristocratie), from Late Latin aristocratia, from Greek aristokratia "government or rule of the best," from aristos "best" (originally "most fitting," from PIE *ar-isto-, superlative form of *ar- "to fit together;" see arm (n.1)) + kratos "rule, power" (see -cracy).

At first in a literal sense of "government by those who are the best citizens;" meaning "rule by a privileged class" (best-born or best-favored by fortune) is from 1570s and became paramount 17c. Hence, the meaning "patrician order" (1650s). In early use contrasted with monarchy; after French and American revolutions, with democracy.
aristocrat (n.): 1789, from French aristocrate, a word of the Revolution, a back-formation from aristocratie (see aristocracy).
aristocratic (adj.): c.1600, "pertaining to aristocracy," from French aristocratique, from Greek aristokratikos "belonging to the rule of the best," from aristokratia (see aristocracy). Meaning "grand, stylish" is from 1845.
aristology (n.): "science of dining," 1835, from Greek ariston "breakfast" (see ere; so called from being the early meal of the day) + -ology. Related: Aristological.
Aristotelian (adj.): also Aristotelean, c.1600, of or pertaining to the person or teachings of Greek philosopher Aristotle (384-322 B.C.E.).
arithmancy (n.): "divination by numbers," 1570s, from Greek arithmos "number" (see arithmetic) + -manteia "divination" (see -mancy).
arithmetic (n.): mid-13c., arsmetike, from Old French arsmetique (12c.), from Latin arithmetica, from Greek arithmetike (tekhne) "(the) counting (art)," fem. of arithmetikos "of or for reckoning, arithmetical," from arithmos "number, counting, amount," from PIE root *re(i)- "to reason, count" (cf. Old English, Old High German rim "number;" Old Irish rim "number," dorimu "I count;" Latin ritus "religious custom;" see read).

Originally in English also arsmetrik, on folk etymology from Medieval Latin ars metrica; spelling corrected early 16c. Replaced native tælcræft, literally "tell-craft."
arithmetical (adj.): 1540s; see arithmetic + -al (1). Related: Arithmetically (late 15c.).
arithmocracy (n.): "rule by numerical majority," 1850, from Greek arithmos "number, counting, amount" (see arithmetic) + -cracy. Related: Arithmocratic; arithmocratical.
arithmomania (n.): "compulsive desire to count objects and make calculations," 1890, from French arithmomanie, from Greek arithmos "number, counting, amount" (see arithmetic) + French -manie (see mania). Related: Arithmomaniac.
Arizona: 1861, originally as the name of a breakaway Confederate region of southern New Mexico; organized roughly along modern lines as a U.S. territory in 1863. From Spanish Arizonac, probably from a local name among the O'odham (Piman) people meaning "having a little spring." Alternative theory is that it derives from Basque arizonak "good oaks."
ark (n.): Old English earc, mainly meaning Noah's but also the Ark of the Covenant, from Latin arca "large box, chest" (see arcane). Also borrowed in Old High German (arahha, Modern German Arche). From the Noachian sense comes extended meaning "place of refuge" (17c.). As the name of a type of ship or boat, from late 15c. In 19c. U.S., especially a large, flat-bottomed river boat to move produce, livestock, etc. to market.
Arkansas: organized as a U.S. territory 1819 (admitted as a state 1836), named for the Arkansas River, which was named for a Siouan tribe.
The spelling of the term represents a French plural, Arcansas, of a name applied to the Quapaw people who lived on the Arkansas River; their name was also written in early times as Akancea, Acansea, Acansa (Dickinson, 1995). This was not the name used by the Quapaws themselves, however. The term /akansa/ was applied to them by Algonquian speakers; this consists of /a-/, an Algonquian prefix found in the names of ethnic groups, plus /kká:ze, a Siouan term refering to members of the Dhegiha branch of the Siouan family. This stem is also the origin for the name of the Kansa tribe and of the state of Kansas; thus the placenames Arkansas and Kansas indirectly have the same origin. [William Bright, "Native American Placenames of the United States," 2004]
arm (n.1): "upper limb," Old English earm "arm," from Proto-Germanic *armaz (cf. Old Saxon, Danish, Swedish, Middle Dutch, German arm, Old Norse armr, Old Frisian erm), from PIE root *ar- "fit, join" (cf. Sanskrit irmah "arm," Armenian armukn "elbow," Old Prussian irmo "arm," Greek arthron "a joint," Latin armus "shoulder"). Arm of the sea was in Old English. Arm-twister "powerful persuader" is from 1938. Arm-wrestling is from 1899.
They wenten arme in arme yfere Into the gardyn [Chaucer]
arm (n.2): "weapon," c.1300, armes (plural) "weapons of a warrior," from Old French armes (plural), "arms, war, warfare," mid-13c., from Latin arma "weapons" (including armor), literally "tools, implements (of war)," from PIE root *ar- "fit, join" (see arm (n.1)). The notion seems to be "that which is fitted together." Meaning "heraldic insignia" (in coat of arms, etc.) is early 14c.; originally they were borne on shields of fully armed knights or barons.
arm (v.): "to furnish with weapons," c.1200, from Old French armer or directly from Latin armare, from arma (see arm (n.2)). Related: Armed; arming.
armada (n.): "fleet of warships," 1530s (erroneously, as armado), from Spanish armada "an armed force," from Medieval Latin armata (see army). Especially of the "Invincible Armada" of Philip II of Spain (1588). Current form of the word is from 1590s.
armadillo (n.): 1570s, from Spanish armadillo, diminutive of armado "armored," from Latin armatus, past participle of armare "to arm" (see arm (n.2)). So called for its hard, plated shell.
Armageddon (n.): "a final conflict," 1811, figurative use of name in Rev. xvi:16, place of the great and final conflict, from Hebrew Har Megiddon "Mount of Megiddo," city in central Palestine, site of important Israeli battles.
armament (n.): c.1600, "munitions of war" (especially the great guns on board a man-of-war), also "naval force equipped for war" (1690s), from Latin armamentum "implement," from Latin armare "to arm, furnish with weapons" from arma (see arm (n.2)). Meaning "process of equipping for war" is from 1813.
armamentarium (n.): 1874, Latin, literally "little arsenal," from armamentum (see armament). Anglicized as armamentary (1731).
armature (n.): c.1400, "an armed force," from Latin armatura "armor, equipment," from armatus, past participle of armare "to arm, furnish with weapons" from arma (see arm (n.2)). Meaning "armor" is mid-15c.; that of "protective covering of a plant or animal" is from 1660s. Electromagnetic sense is from 1835.