Online Etymology Dictionary

essence: late 14c., from L. essentia "being, essence," abstract n. formed in imitation of Gk. ousia "being, essence" (from on, gen. ontos, prp. of einai "to be"), from prp. stem of esse "to be," from PIE *es- (cf. Skt. asmi, Hittite eimi, O.C.S. jesmi, Lith. esmi, Goth. imi, O.E. eom "I am;" see be). Originally "substance of the Trinity," the general sense of "basic element of anything" is first recorded in English 1650s, though this is the base meaning of the first English use of essential (mid-14c.).
quintessence: early 15c., in ancient and medieval philosophy, "pure essence, substance of which the heavenly bodies are composed," lit. "fifth essence," from M.Fr. quinte essence (14c.), from M.L. quinta essentia, from L. quinta, fem. of quintus "fifth" + essentia (see essence). Loan-translation of Gk. pempte ousia, the "ether" added by Aristotle to the four known elements (water, earth, fire, air) and said to permeate all things. Its extraction was one of the chief goals of alchemy. Sense of "purest essence" (of a situation, character, etc.) is first recorded 1580s.
essential: mid-14c., "that is such by its essence," from L.L. essentialis, from essentia (see essence). Meaning "pertaining to essence" is from late 14c., that of "constituting the essence of something" is from 1540s; that of "necessary" is from 1520s. Essentials "indispensible elements" is from early 16c. Related: Essentially; essentialism (1939); essentialist..
sum: late 13c., "quantity or amount of money," from Anglo-Fr. and O.Fr. summe (13c.), from L. summa "total number, whole, essence, gist," noun use of fem. of summus "highest," from PIE *sup-mos-, from base *uper "over" (see super-). The sense development from "highest" to "total number" is probably via the Roman custom of adding up a stack of figures from the bottom and writing the sum at the top, rather than at the bottom as we do now (cf. the bottom line). Meaning "total number of anything" is recorded from late 14c. Meaning "essence of a writing or speech" also is attested from late 14c. The verb is attested from c.1300; meaning "briefly state the substance of" (now usually with up) is first recorded 1621. Sum-total is attested from c.1395, from M.L. summa totalis.
attar: 1798, from Pers. 'atar-gul "essence of roses," from 'atar "fragrance," from Arabic 'utur "perfumes, aromas."
quiddity: 1539, "captious nicety in argument" from M.L. quidditas, lit. "whatness," from L. quid "what," neut. of quis (see who). Sense developed from scholastic disputes over the nature of things. Original meaning "real essence or nature of a thing" is attested in Eng. from 1569.
virtual: late 14c., "influencing by physical virtues or capabilities," from M.L. virtualis, from L. virtus "excellence, potency, efficacy," lit. "manliness, manhood" (see virtue). The meaning of "being something in essence or fact, though not in name" is first recorded 1650s, probably via sense of "capable of producing a certain effect" (early 15c.). Computer sense of "not physically existing but made to appear by software" is attested from 1959.
Bodhisattva: 1828, from Skt., lit. "one whose essence is perfect knowledge," from bodhi "perfect knowledge" (see Buddha) + sattva "reality, being."
suttee: "self-cremation of a Hindu widow on her husband's funeral pyre," 1786, from Hindi, from Skt. sati "virtuous woman," fem. of sat "good, wise," lit. "existing," prp. of asmi "I am" (cognate with L. esse; see essence). Properly, the word for the woman who does so. The custom was abolished in British India in 1829.
ontogeny: "development of an individual," 1872, coined from Gk. on (gen. ontos) "being" (prp. of einai "to be;" see essence) + -geneia "origin," from -genes "born."
ontology: "metaphysical science or study of being," 1721, from Mod.L. ontologia (coined in Fr. by Jean le Clerc, 1692), from Gk. on (gen. ontos) "being" (prp. of einai "to be;" see essence) + -logia "writing about, study of."
ontic: 1949, from Gk. ont-, comb. form of on (gen. ontos) "being," prp. of einai "to be" (see essence).
absinthe: alcoholic liqueur distilled from wine mixed with wormwood, 1842, from Fr. absinthe, "essence of wormwood," from Mod.L. (Linnaeus) name for the plant (Artemisia Absinthium), from L. absinthum, from Gk. apsinthion, perhaps from Persian (cf. Pers. aspand, of the same meaning). The plant so called in English from 1610s.
gist: 1711, "the real point" (of a law case, etc.), from Anglo-Fr. legalese phrases, especially cest action gist "this action lies," meaning "this case is sustainable by law," from O.Fr. gist en "it consists in, it lies in" (third pers. sing. pres. indicative of gésir "to lie"), from L. jacet "it lies." Extended sense of "essence" first recorded 1823.
atman: 1785, from Skt. atma "essence, breath, soul," from PIE *etmen "breath" (a root found in Skt. and Gmc.; cf. O.E. æðm, Du. adem, O.H.G. atum "breath," O.E. eþian, Du. ademen "to breathe").
rosemary: c.1440, earlier rosmarine (c.1300), from L. rosmarinus, lit. "dew of the sea" (cf. Fr. romarin), from ros "dew" + marinus (see marine). Perhaps so called because it grew near coasts. Form altered in Eng. by influence of rose and Mary. L. ros is from PIE *ras-/*eras- "to flow, wet, moisten" (cf. Lith. rasa, O.C.S. rosa "dew," Skt. rasah "sap, juice, fluid, essence," Hitt. arszi "flows," and perhaps also Rha, Scythian name of the River Volga (see rhubarb)).
substance: c.1300, "essential nature," from O.Fr. substance (12c.), from L. substantia "being, essence, material," from substans, prp. of substare "stand firm, be under or present," from sub "up to, under" + stare "to stand," from PIE base *sta- "to stand" (see stet). A loan-translation of Gk. hypostasis. Sense of "the matter of a study, discourse, etc." first recorded late 14c. Meaning "any kind of corporeal matter" also is first attested late 14c.
mutual: late 15c., originally of feelings, from M.Fr. mutuel (14c.), from L. mutuus "reciprocal, done in exchange," from PIE base *mei- "to change" (see mutable).
"The essence of its meaning is that it involves the relation x is or does to y as y to x; & not the relation, x is or does to z as y to z" [Fowler]
Mutual Admiration Society (1851) seems to have been coined by Thoreau. Mutual fund is recorded from 1950.
swastika: Greek cross with arms bent at right angles, 1871 (later specifically as emblem of the Nazi party, 1932), from Skt. svastika-s, lit. "being fortunate," from svasti-s "well-being, luck," from su- "well" + as-, root of asti "(he) is," from root of L. esse "to be" (see essence). Also known as gammadion and fylfot. Originally an ancient cosmic or religious symbol thought to bring good luck. Use in reference to the Nazi emblem first recorded in Eng. in 1932. The Ger. word was Hakenkreuz, lit. "hook-cross."
air (2): "assumed manner, affected appearance," 1650s (especially in phrase put on airs, 1781), perhaps via Fr. air "look, appearance, mien, bearing, tone" (O.Fr. aire "reality, essence, nature, descent, extraction" 12c.; cf. debonair), from L. ager "place, field" (see acre) on notion of "place of origin." Air in the sense of "manner, appearance" (e.g. an air of mystery) is attested in English from 1590s, an independent adoption of Fr. air. But perhaps these senses in English also developed from or were infl. by air (1); cf. L. spiritus "breath, breeze," also "high spirit, pride," and the extended senses of anima.