alchemy

Etymology

From Old French alkimie, arquemie (French alchimie), from Medieval Latin alchēmia, from Arabic اَلْكِيمِيَاء (al-kīmiyāʔ), from Ancient Greek χυμείᾱ (khumeíā, “art of alloying metals”), perhaps from Χημία (Khēmía, “black earth (ancient name for Egypt)”) and/or χυμός (khumós, “juice, sap”). Compare Spanish alquimia and Italian alchimia.

noun

1. (uncountable) The premodern and early modern study of physical changes, particularly in Europe, Arabia, and China and chiefly in pursuit of an elixir of immortality, a universal panacea, and/or a philosopher's stone able to transmute base metals into gold, eventually developing into chemistry.
   And yet surely to alchemy this right is due, that it may be compared to the husbandman whereof Æsop makes the fable; that, when he died, told his sons that he had left unto them gold buried underground in his vineyard; and they digged over all the ground, and gold they found none; but by reason of their stirring and digging the mould about the roots of their vines, they had a great vintage the year following: so assuredly the search and stir to make gold hath brought to light a great number of good and fruitful inventions and experiments, as well for the disclosing of nature as for the use of man’s life. 1605, Francis Bacon, The Advancement of Learning, IV. (11)
   The [Isaac] Newton that emerges from the [unpublished] manuscripts is far from the popular image of a rational practitioner of cold and pure reason. The architect of modern science was himself not very modern. He was obsessed with alchemy. 2014-06-21, “Magician’s brain”, in The Economist, volume 411, number 8892
   The purpose of physical alchemy—as opposed to its various spiritual pursuits—was to treat the supposed leprosity of base metals such as lead, refining and purifying them into gold.
2. (countable) The causing of any sort of mysterious sudden transmutation.
   1640, George Herbert, Jacula Prudentum; or, Outlandish Proverbs, Sentences, etc., in The Remains of that Sweet Singer of the Temple George Herbert, London: Pickering, 1841, p. 143, No alchymy to saving.
   [Poetry] transmutes all that it touches, and every form moving within the radiance of its presence is changed by wondrous sympathy to an incarnation of the spirit which it breathes: its secret alchemy turns to potable gold the poisonous waters which flow from death through life; it strips the veil of familiarity from the world, and lays bare the naked and sleeping beauty, which is the spirit of its forms. 1840, Percy Bysshe Shelley, A Defence of Poetry
   There is such a rich thesaurus now of things that I have said that have been, one way or another, through what alchemy I do not know, somehow misconstrued, that it would really take me too long to engage in a full global itinerary of apology to all concerned. 2016, Boris Johnson, (Please provide the book title or journal name)
3. (computing, slang, countable) Any elaborate transformation process or algorithm.