Online Etymology Dictionary

conservation of energy: apparently coined in French by Leibnitz in 1692; attested in English from early 18c. as conservatio virum vivarum or partially nativized versions of it. The exact phrase is attested from 1853.
conservationist (n.): 1870, from conservation + -ist. The ecological sense is from 1922.
conservatism (n.): 1835, in reference to the Conservative party in British politics; from conservative + -ism. From 1840 in reference to conservative principles generally.
conservative (adj.): late 14c., conservatyf, from Middle French conservatif, from Late Latin conservativus, from Latin conservatus, past participle of conservare (see conserve).

As a modern political tradition, conservatism traces to Edmund Burke's opposition to the French Revolution (1790), but the word conservative is not found in his writing. It was coined by his French disciples, (such as Chateaubriand, who titled his journal defending clerical and political restoration "Le Conservateur").

Conservative as the name of a British political faction first appeared in an 1830 issue of the "Quarterly Review," in an unsigned article sometimes attributed to John Wilson Croker. It replaced Tory (q.v.) by 1843, reflecting both a change from the pejorative name (in use for 150 years) and repudiation of some reactionary policies. Extended to similar spirits in other parties from 1845.
Strictly speaking, conservatism is not a political system, but rather a way of looking at the civil order. The conservative of Peru ... will differ greatly from those of Australia, for though they may share a preference for things established, the institutions and customs which they desire to preserve are not identical. [Russell Kirk (1918-1994)]
Phrases such as a conservative estimate make no sense etymologically. The noun is attested from 1831, originally in the British political sense.
conservator (n.): c. 1400, from Anglo-French conservatour, from Latin conservator "keeper, preserver, defender," agent noun of conservare (see conserve).
conservatorship (n.): 1640s, from conservator + -ship.
conservatory (n.): 1560s, "preservative;" 1660s, "greenhouse," from stem of conservation + -ory. In sense "school for performing arts" it is recorded from 1842, from Italian conservatorio or French conservatoire, originally "hospital for foundlings in which musical education was given."
conserve (v.): late 14c., from Old French conserver (9c.), from Latin conservare "to keep, preserve, keep intact, guard," from com-, intensive prefix (see com-), + servare "keep watch, maintain" (see observe). Related: Conserved; conserving. As a noun (often conserves) from late 14c.
consider (v.): late 14c., from Old French considerer (13c.) "reflect on, consider, study," from Latin considerare "to look at closely, observe," perhaps literally "to observe the stars," from com- "with" (see com-) + sidus (genitive sideris) "constellation" (see sidereal).

Perhaps a metaphor from navigation, but more likely reflecting Roman obsession with divination by astrology. Tucker doubts the connection with sidus, however, because it is "quite inapplicable to desiderare," and suggests derivation instead from the PIE root of English side meaning "stretch, extend," and a sense for the full word of "survey on all sides" or "dwell long upon." Related: Considered; considering.
considerable (adj.): mid-15c., "capable of being considered," from Medieval Latin considerabilis "worthy to be considered," from Latin considerare (see consider). Meaning "pretty large" is from 1640s (implied in considerably).
CONSIDERABLE. This word is still frequently used in the manner pointed out by Dr. Witherspoon in the following remark: "He is considerable of a surveyor; considerable of it may be found in the country. This manner of speaking prevails in the northern parts." [Pickering, 1816]
considerate (adj.): 1570s, "marked by deliberation," from Latin consideratus, past participle of considerare (see consider). Of persons, "deliberate, prudent," 1580s; meaning "showing consideration for others" is from c. 1700. Related: Considerately; considerateness.
consideration (n.): mid-14c., "a beholding, looking at," also "keeping in mind," from Old French consideracion (12c., Modern French considération), from Latin considerationem (nominative consideratio) "consideration, contemplation, reflection," noun of action from past participle stem of considerare (see consider). Meaning "a taking into account" is from mid-15c.; that of "something given in payment" is from c. 1600.
consign (v.): early 15c., "to ratify by a sign or seal," from Middle French consigner (15c.), from Latin consignare "to seal, register," originally "to mark with a sign," from com- "together" (see com-) + signare "to sign, mark," from signum "sign" (see sign (n.)). Commercial sense is from 1650s. Related: Consignee; consignor.
consignment (n.): 1560s, "sealing with a sign," from consign + -ment. Meaning "delivering over" is from 1660s; especially of goods, for the sake of sale or auction, from c. 1700. Meaning "quantity of goods so assigned" is recorded from 1720s.
consilience (n.): 1840, "concurrence, coincidence," literally "a jumping together," formed on model of resilience from Latin consilient-, from com- "together" (see com-) + salire "to leap" (see salient (adj.)).
consist (v.): 1520s, from Middle French consister (14c.) or directly from Latin consistere "to stand firm, take a standing position, stop, halt," from com- "together" (see com-) + sistere "to place," causative of stare "to stand, be standing" (see stay (v.)). Related: Consisted; consisting.
consistence (n.): c. 1600, "state of standing still; firmness," from Middle French consistence (Modern French consistance) "a standing fast," from Medieval Latin consistentia, from Latin consistentem (nominative consistens), present participle of consistere (see consist). Meaning "coherence, solidity" is recorded from 1620s.
consistency (n.): 1590s, "firmness of matter," from Medieval Latin consistentia or directly from Latin consistentem, from consistere (see consist). Meaning "state of being in agreement or harmony" (with something) is from 1650s; meaning "self-consistent" is from 1716.
consistent (adj.): 1570s, "standing firm, standing still," from Latin consistentem (nominative consistens), present participle of consistere (see consist). Modern sense of "agreeing" (with with) is first attested 1640s. Older sense survives in consistency. Related: Consistently.
consistory (n.): c. 1300, "secular tribunal," from Old North French consistorie (Old French consistoire, 12c.) and directly from Late Latin consistorium "waiting room, meeting place of the imperial council," from Latin consistere (see consist). Meaning "Church council" is from early 14c.
consol (n.): alternative form of console (n.).
consolate (v.): late 15c., from Latin consolatus, past participle of consolari (see console (v.)); obsolete and replaced by console (v.).
consolation (n.): late 14c., "act of consoling," from Old French consolacion (11c., Modern French consolation) "solace, comfort; delight, pleasure," from Latin consolationem (nominative consolatio-) "consoling, comforting," noun of action from consolat-, past participle stem of consolari (see console (v.)). Consolation prize is recorded from 1886.
consolations (n.): c. 1400, "act of consolation;" see consolation.
consolatory (adj.): early 15c., from Latin consolatorius, from consolator, agent noun from consolari (see console (v.)).
console (v.): 1690s, from French consoler "to comfort, console," from Latin consolari "offer solace, encourage, comfort, cheer," from com-, intensive prefix (see com-), + solari "to comfort" (see solace). Or perhaps a back-formation from consolation. The Latin word is glossed in Old English by frefran. Related: Consoled; consoling.
console (n.): 1706, "a cabinet; an ornamental base structure," from French console "a bracket" (16c.), which is of uncertain origin, possibly from Middle French consolateur, literally "one who consoles," word used for carved human figures supporting cornices, shelves or rails in choir stalls. Another guess connects it to Latin consolidare. Sense evolved to "body of a musical organ" (1881), "radio cabinet" (1925), then "cabinet for a TV, stereo, etc." (1944).
consolidate (v.): 1510s, "to compact into one body," from Latin consolidatus, past participle of consolidare "to make solid," from com- "together" (see com-) + solidare "to make solid" (see solid). Meaning "to make firm or strong" is from mid-16c. Related: Consolidated; consolidating.
consolidated (adj.): past participle adjective from consolidate. Of money, debt, etc., from 1753; in literal sense of "made firm, unified," from c. 1850.
consolidation (n.): c. 1400, from Late Latin consolidationem (nominative consolidatio), noun of action from past participle stem of consolidare "to make firm, consolidate," from com- "together" (see com-) + solidare "to make solid," from solidus (see solid).
consomme (n.): 1815, from French consommé, noun use of past participle of consommer "to consume" (12c.), from Latin consummare "to complete, finish, perfect" (see consummation). The French verb was influenced in sense by Latin consumere "to consume."
consonance (n.): early 15c., "agreement among persons," from Old French consonance (12c.) "consonance, rhyme," from Latin consonantia "harmony, agreement," from consonantem (nominative consonans) (see consonant). Meaning "correspondence of sounds" is from 1580s.
consonant (n.): early 14c., "sound other than a vowel," from Latin consonantem (nominative consonans), present participle of consonare "to sound together, sound aloud," from com- "with" (see com-) + sonare "to sound" (see sonata). Consonants were thought of as sounds that are only produced together with vowels.
consonant (adj.): early 15c., from Old French consonant (13c.), from Latin consonantem (nominative consonans), present participle of consonare (see consonant (n.)).
consort (n.): early 15c., "partner," from Middle French consort "colleague, partner, wife" (14c., Old French consorte), from Latin consortem (nominative consors) "partner, comrade; wife, brother, sister," noun use of adjective meaning "having the same lot, of the same fortune," from com- "with" (see com-) + sors "a share, lot" (see sort (n.)). Sense of "husband or wife" ("partner in marriage") is 1630s in English.
consort (v.): 1580s, from consort (n.). Related: Consorted; consorting. Confused in form and sense with concert since 1580s.
consortia (n.): plural of consortium.
consortium (n.): 1829, from Latin consortium "fellowship, participation, society," from consors (genitive consortis; see consort (n.)). Earlier, in British law, a term for "right of husband's access to his wife."
conspecific (adj.): 1859, from conspecies (1837), from con- "with" + specific, here representing species (n.). From 1962 as a noun.
conspectus (n.): 1836, from Latin conspectus "a looking at, sight, view; range or power of vision," from past participle of conspicere "to look at" (see conspicuous).
conspicuous (adj.): 1540s, from Latin conspicuus "visible, open to view, striking," from conspicere "to look at, observe, see, notice," from com-, intensive prefix (see com-), + specere (see scope (n.1)). Phrase conspicuous by its absence (1859) is said to be from Tacitus ("Annals" iii.76), in a passage about certain images: "sed præfulgebant ... eo ipso quod effigies eorum non visebantur."
conspiracy (n.): mid-14c., from Anglo-French conspiracie, Old French conspiracie "conspiracy, plot," from Latin conspirationem (nominative conspiratio) "agreement, union, unanimity," noun of action from conspirare (see conspire); earlier in same sense was conspiration (early 14c.), from French conspiration (13c.), from Latin conspirationem. An Old English word for it was facengecwis. As a term in law, from 1863. Conspiracy theory is from 1909.
conspirator (n.): c. 1400, conspyratour, from Old French conspirateur, from Latin conspiratorem (nominative conspiratorio), noun of action from conspirat-, past participle stem of conspirare (see conspire). Fem. form conspiratress is from mid-18c. Related: Conspiratorial; conspiratorially; conspiratory.
conspire (v.): late 14c., from Old French conspirer (14c.), from Latin conspirare "to agree, unite, plot," literally "to breathe together," from com- "together" (see com-) + spirare "to breathe" (see spirit (n.)). Or perhaps the notion is "to blow together" musical instruments, i.e., "To sound in unison." Related: Conspired; conspiring.
constable (n.): c. 1200, "chief household officer, justice of the peace," from Old French conestable (12c., Modern French connétable), "steward, governor," principal officer of the Frankish king's household, from Late Latin comes stabuli, literally "count of the stable" (established by Theodosian Code, c.438 C.E.), hence, "chief groom." See count (n.). Second element is from Latin stabulum "stable, standing place" (see stable (n.)). Probably a translation of a Germanic word. Meaning "an officer of the peace" is from c. 1600, transferred to "police officer" 1836. French reborrowed constable 19c. as "English police."
constabulary (n.): 1630s, "district under a constable," from Medieval Latin constabularia, from constabulus, Latinized form of Old French conestable (see constable). Meaning "organized body of constables" is from 1837. Earlier (mid-15c.) as an adjective, "pertaining to a constable."
constance (n.): mid-14c., "steadfastness," from Old French constance "steadfastness, permanence" (14c.), from Latin constantia (source of Italian costanza, Spanish constancia), noun of action from constantem (see constant (adj.)). Obsolete since 17c. except as a given name for a girl, which enjoyed a mild popularity in U.S. c. 1945-1955.
constancy (n.): 1520s, from constance + -cy.
constant (adj.): late 14c., "steadfast, resolute," from Old French constant (14c.) or directly from Latin constantem (nominative constans) "standing firm, stable, steadfast, faithful," present participle of constare, from com- "together" (see com-) + stare "to stand," from PIE root *stā- "to stand" (see stet). Of actions and conditions from 1650s. Related: Constantly.
constant (n.): 1832 in mathematics and physics, from constant (adj.).