Online Etymology Dictionary

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.
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.), 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: Consolidatedconsolidating.
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, from sonus "sound" (see sound (n.1)). 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).