Etymology
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polymath (n.)

"person of various learning," 1620s, from Greek polymathēs "having learned much, knowing much," from polys "much" (from PIE root *pele- (1) "to fill") + root of manthanein "to learn" (from PIE root *mendh- "to learn"). Related: Polymathy "acquaintance with many branches of learning" (1640s, from Greek polymathia "much learning"); polymathic.

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*mendh- 

Proto-Indo-European root meaning "to learn." It forms all or part of: chrestomathy; mathematic; mathematical; mathematics; opsimathy; polymath.

It is the hypothetical source of/evidence for its existence is provided by: Greek menthere "to care," manthanein "to learn," mathēma "science, knowledge, mathematical knowledge;" Lithuanian mandras "wide-awake;" Old Church Slavonic madru "wise, sage;" Gothic mundonsis "to look at," German munter "awake, lively."

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*pele- (1)
*pelə-, Proto-Indo-European root meaning "to fill," with derivatives referring to abundance and multitude.

It forms all or part of: accomplish; complete; compliment; comply; depletion; expletive; fele; fill; folk; full (adj.); gefilte fish; hoi polloi; implement; manipulation; nonplus; plebe; plebeian; plebiscite; pleiotropy; Pleistocene; plenary; plenitude; plenty; plenum; plenipotentiary; pleo-; pleonasm; plethora; Pliocene; pluperfect; plural; pluri-; plus; Pollux; poly-; polyamorous; polyandrous; polyclinic; polydactyl; polydipsia; Polydorus; polyethylene; polyglot; polygon; polygraph; polygyny; polyhedron; polyhistor; polymath; polymer; polymorphous; Polynesia; polyp; Polyphemus; polyphony; polysemy; polysyllabic; polytheism; replenish; replete; supply; surplus; volkslied.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit purvi "much," prayah "mostly;" Avestan perena-, Old Persian paru "much;" Greek polys "much, many," plethos "people, multitude, great number," ploutos "wealth;" Latin plus "more," plenus "full;" Lithuanian pilus "full, abundant;" Old Church Slavonic plunu; Gothic filu "much," Old Norse fjöl-, Old English fela, feola "much, many;" Old English folgian; Old Irish lan, Welsh llawn "full;" Old Irish il, Welsh elu "much."
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anticyclone (n.)

"outward rotary flow of air from an area of atmospheric high pressure," 1863, coined by Francis Galton, English polymath, explorer, and meteorologist, from anti- + cyclone. Related: Anticyclonic.

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cation (n.)

1834, from Latinized form of Greek kation "going down," neuter present participle of katienai "to go down," from kata "down" (see cata-) + ienai "to go" (from PIE root *ei- "to go"). Proposed by the Rev. William Whewell, English polymath, and published by English physicist Michael Faraday. Compare ion.

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ion (n.)
1834, introduced by English physicist and chemist Michael Faraday (suggested by the Rev. William Whewell, English polymath), coined from Greek ion, neuter present participle of ienai "go," from PIE root *ei- "to go." So called because ions move toward the electrode of opposite charge.
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anode (n.)

1834, coined from Greek anodos "way upward," from ano "upward," from ana "up" (see ana-) + hodos "a way," a word of uncertain origin (see Exodus). Proposed by the Rev. William Whewell, English polymath, and published by English chemist and physicist Michael Faraday. So called from the path the electrical current was thought to take. Compare cathode. Related: Anodic, anodal.

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astigmatism (n.)

"defect in the structure of the eye whereby the rays of light do not converge to a point upon the retina," 1849, coined by the Rev. William Whewell, English polymath, from Greek a- "without" (see a- (3)) + stigmatos genitive of stigma "a mark, spot, puncture," from PIE root *steig- "to stick; pointed" (see stick (v.)).

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electrolysis (n.)

"decomposition into constituent parts by an electric current," 1834; the name was introduced by Faraday on the suggestion of the Rev. William Whewell, English polymath, from electro- + Greek lysis "a loosening," from lyein "to loosen, set free" (from PIE root *leu- "to loosen, divide, cut apart"). Originally of tumors, later (1879) of hair removal. Related: electrolytic.

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anion (n.)

"a negatively charged ion, which moves toward the anode (q.v.) during electrolysis," 1834, proposed by the Rev. William Whewell, English polymath, and published by English physicist Michael Faraday, from Greek anion "(thing) going up," neuter past participle of anienai "go up," from ana "up" (see ana-) + ienai "go" (from PIE root *ei- "to go"). Related: Anionic.

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