Online Etymology Dictionary

conquer (v.): c.1200, cunquearen, from Old French conquerre "conquer, defeat, vanquish," from Vulgar Latin *conquaerere (for Latin conquirere) "to search for, procure by effort, win," from Latin com-, intensive prefix (see com-), + quaerere "to seek, gain" (see query (v.)). Related: Conquered; conquering.
conquerer (n.): obsolete form of conqueror; see -er.
conqueror (n.): c.1300, from Anglo-French conquerour, Old French conquereor, from Old French conquerre (see conquer). Another early form was conquestor. William the Conqueror so called from early 12c. in Anglo-Latin: Guillelmus Magus id est conquæstor rex Anglorum.
conquest (n.): early 14c., a merged word from Old French conquest "acquisition" (Modern French conquêt), and Old French conqueste "conquest, acquisition" (Modern French conquête), both from past participle of conquerre, from Vulgar Latin *conquaerere (see conquer).
conquistador (n.): 1830, from Spanish conquistador, literally "conqueror," noun of action from conquistar "to conquer," from Vulgar Latin conquistare, from Latin conquistus, past participle of conquirere "to seek for" (see conquer).
Conrad: masc. proper name, from Old High German Kuonrat, literally "bold in counsel," from kuon "bold" + rat "counsel" (see read (v.)).
consanguine (adj.): c.1600, from French consanguin (14c.), from Latin consanguineus "of the same blood" (see consanguinity).
consanguineous (adj.): c.1600, from Latin consanguineus "of the same blood" (see consanguinity).
consanguinity (n.): c.1400, from Middle French consanguinité, from Latin consanguinitatem (nominative consanguinitas), from consanguineus "consanguineous, of the same blood," from com- "together" (see com-) + sanguineus "of blood" (see sanguine).
conscience (n.): early 13c., from Old French conscience "conscience, innermost thoughts, desires, intentions; feelings" (12c.), from Latin conscientia "knowledge within oneself, sense of right, a moral sense," from conscientem (nominative consciens), present participle of conscire "be (mutually) aware," from com- "with," or "thoroughly" (see com-) + scire "to know" (see science).

Probably a loan-translation of Greek syneidesis, literally "with-knowledge." Sometimes nativized in Old English/Middle English as inwit. Russian also uses a loan-translation, so-vest, "conscience," literally "with-knowledge."
conscient (adj.): c.1600, "conscious," from Latin conscientem, present participle of conscire "to be conscious" (see conscience). Also with meaning "a conscious being" (c.1770).
conscientious (adj.): 1610s, from Middle French conscientieux (16c.; Modern French consciencieux), from Medieval Latin conscientiosus, from conscientia (see conscience). Related: Conscientiously; conscientiousness.
conscientious objector (n.): 1896, in reference to those with religious scruples about mandatory vaccination. Military sense predominated from World War I.
After a chequered career full of startling episodes and reversals, the Vaccination Bill becomes virtually the Vaccination Act. In Parliament the hottest of the contest centred round the conscientious objector. [The Lancet, Aug. 13, 1898]
conscionable (adj.): 1540s, from conscioned "having a conscience" (from conscience) + -able; obsolete from early 18c. but fossilized in its negative, unconscionable.
conscious (adj.): c.1600, "knowing, privy to," from Latin conscius "knowing, aware," from conscire (see conscience); probably a loan-translation of Greek syneidos. A word adopted from the Latin poets and much mocked at first. Sense of "active and awake" is from 1837.
consciousness (n.): 1630s, "internal knowledge," from conscious + -ness. Meaning "state of being aware" is from 1746.
conscript (n.): 1800, perhaps a back-formation (influenced by French adjective conscrit) from conscription.
conscript (v.): 1813, American English, from conscript (n.). A word from the militia drafts in the War of 1812. Popularized (or unpopularized) during U.S. Civil War, when both sides resorted to it in 1862. Related: Conscripted; conscripting.
conscript (adj.): 1530s, from Latin conscriptus, past participle of conscribere "to draw up, list," literally "to write together" (see conscription).
conscription (n.): late 14c., "a putting in writing," from Middle French conscription, from Latin conscriptionem (nominative conscriptio) "a drawing up of a list, enrollment, a levying of soldiers," from conscribere "to enroll," from com- "with" (see com-) + scribere "to write" (see script). Meaning "enlistment of soldiers" is from 1520s; the sense "compulsory enlistment for military service" (1800) is traceable to the French Republic act of Sept. 5, 1798. Technically, a conscription is the enrollment of a fixed number by lot, with options of providing a substitute.
consecrate (v.): late 14c., from Latin consecratus, past participle of consecrare "to make holy, devote," from com- "together" (see com-) + sacrare (see sacred). Related: Consecrated; consecrating.
consecration (n.): late 14c., from Latin consecrationem (nominative consecratio), noun of action from consecrat-, past participle stem of consecrare (see consecrate).
consecutive (adj.): 1610s, from French consécutif (16c.), from Medieval Latin consecutivus, from Latin consecutus "following closely," past participle of consequi (see consequence). Related: Consecutively.
consensual (adj.): 1754, "having to do with consent," from stem of Latin consensus (see consensus) + -al (1). Meaning "by consent" is attested from 1800.
consensus (n.): 1854 as a term in physiology; 1861 of persons; from Latin consensus "agreement, accord," past participle of consentire (see consent). There is an isolated instance of the word from 1633.
consent (v.): early 13c., from Old French consentir (12c.) "agree, comply," from Latin consentire "feel together," from com- "with" (see com-) + sentire "to feel" (see sense (n.)). "Feeling together," hence, "agreeing, giving permission," apparently a sense evolution that took place in French before the word reached English. Related: Consented; consenting.
consent (n.): c.1300, "approval," also "agreement in sentiment, harmony," from Old French consente, from consentir (see consent (v.)). Age of consent is attested from 1809.
consequence (n.): late 14c., "inference, conclusion," from Old French consequence "result" (13c., Modern French conséquence), from Latin consequentia, from consequentem (nominative consequens), present participle of consequi "to follow after," from com- "with" (see com-) + sequi "to follow" (see sequel). Sense of "importance" (c.1600) is from notion of being "pregnant with consequences."
consequences (n.): see consequence. As the name of a round game, attested from 1796.
consequent (adj.): late 14c., in various senses now restricted to consequence, from Middle French conséquent "following, resulting," from Latin consequentem (nominative consequens); see consequence. Meaning "an event which follows another" is from 1610s. Mathematical sense is from 1560s. Related: Consequently.
consequential (adj.): 1620s, from consequent (Latin consequentia) + -al (1). Meaning "pregnant with consequences, important" is recorded from 1728. Related: Consequentially (c.1600).
consequentialism (n.): 1969, from consequential + -ism. The philosophy that the morality of an action is to be judged solely by its consequences. Related: Consequentialist.
conservancy (n.): 1755, "commission with jurisdiction over a port or river," from Latin conservant-, present participle stem of conservare (see conserve) + -cy. Earlier was conservacy (mid-15c., Anglo-French conservacie). Meaning "official preservation of undeveloped land" dates from 1859 (first reference is to protection of bo trees in Ceylon).
conservation (n.): late 14c., conservacioun, "preservation of one's health and soundness," from Latin conservationem (nominative conservatio) "a keeping, preserving, conserving," noun of action from past participle stem of conservare (see conserve). Meaning "preservation of existing conditions" in any sense is from mid-15c. Since late 15c., in reference to English municipal authorities who had charge of rivers, sewers, forests, fisheries, etc. Specifically of the environment from 1922.
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, (e.g. 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 out by Dr. Witherspoon in the following remark: "He is considerable of a surveyor; considerable of it may found in the country. This manner of speaking 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).
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 be standing" (see assist). Related: Consisted; consisting.