Online Etymology Dictionary

conjuration (n.): late 14c., coniuracioun, "conspiracy" (now obsolete), also "a calling upon something supernatural," from Old French conjuracion "spell, incantation, formula used in exorcism," from Latin coniurationem (nominative coniuratio) "a swearing together, conspiracy," noun of action from coniurare (see conjure).
conjure (v.): late 13c., "command on oath," from Old French conjurer "invoke, conjure" (12c.), from Latin coniurare "to swear together; conspire," from com- "together" (see com-) + iurare "to swear" (see jury (n.)). Magical sense is c.1300, for "constraining by spell" a demon to do one's bidding. Related: Conjured; conjuring. Phrase conjure up "cause to appear in the mind" (as if by magic) attested from 1580s.
conjurer (n.): late 14c., from Anglo-French conjurour, Old French conjureur "conjurer, magician, exorcist," from Latin coniurator, from coniurare (see conjure).
conk (v.): as in conk out, 1918, coined by World War I airmen, perhaps in imitation of the sound of a stalling motor, reinforced by conk (v.) "hit on the head," originally "punch in the nose" (1821), from conk (n.), slang for "nose" (1812), perhaps from fancied resemblance to a conch (pronounced "conk") shell.
conker (n.): "snail shell," also "horse chestnut," from children's game of conkers (q.v.).
conkers (n.): "child's game played with horse chestnuts," originally with snail shells, 1847, probably a variant of conquer. The goal was to break the other player's item by hitting it with yours.
connate (adj.): 1640s, from Late Latin connatus "born together, twins," past participle of connasci "to be born together," from com- "together" (see com-) + nasci "to be born" (Old Latin gnasci; see genus). Related: Connation.
connect (v.): mid-15c., from Latin conectere "join together" (see connection). Displaced 16c. by connex (1540s), from Middle French connexer, from Latin *connexare, a supposed frequentative of conectere (past participle stem connex-). Connect was re-established 1670s.

A similar change took place in French, where connexer was superseded by connecter. Meaning "to establish a relationship" (with) is from 1881. Slang meaning "get in touch with" is attested by 1926, from telephone connections. Meaning "awaken meaningful emotions, establish rapport" is from 1942. Of a hit or blow, "to reach the target," from c.1920. Related: Connected; connecting; connectedness.
Connecticut: U.S. state, originally the name of the river, said to be from Mohican (Algonquian) quinnitukqut "at the long tidal river," from *kwen- "long" + *-ehtekw "tidal river" + *-enk "place."
connection (n.): late 14c., conneccion, later connexioun (mid-15c.), from Old French connexion, from Latin connexionem (nominative connexio) "a binding or joining together," from *connexare, frequentative of conectere "to fasten together, to tie, join together," from com- "together" (see com-) + nectere "to bind, tie" (see nexus).

Spelling shifted from connexion to connection (especially in American English) mid-18c. under influence of connect, abetted by affection, direction, etc.
connective (adj.): 1650s, from connect + -ive (if from Latin, it likely would have been *connexive). Connective tissue is from 1839.
connectivity (n.): 1893, from connective + -ity.
connector (n.): 1795, "tube for connecting other materials," agent noun in Latin form from connect and usefully distinct from connecter.
connexion (n.): see connection.
conniption (n.): 1833, American English, origin uncertain; perhaps related to corruption, which was used in a sense of "anger" from 1799, or from English dialectal canapshus "ill-tempered, captious," probably a corruption of captious.
connivance (n.): the main modern form of connivence (q.v.).
connive (v.): c.1600, from Latin connivere, also conivere "to wink," hence, "to wink at (a crime), be secretly privy," from com- "together" (see com-) + base akin to nictare "to wink," from PIE root *kneigwh- (see nictitate). Related: Connived; conniving.
connivence (n.): 1590s, from Latin conniventia, from conniventem (nominative connivens), present participle of connivere (see connive). Spelling with -a- prevailed after early 18c., but is not etymological.
connivent (adj.): 1640s, from Latin conniventem (nominative connivens), present participle of connivere (see connive).
conniving (adj.): 1783, present participle adjective from connive. Earlier in this sense was connivent.
connoisseur (n.): 1714, from French connoisseur (Modern French connaiseur), from Old French conoisseor "an expert, a judge, one well-versed," from conoistre "to know," from Latin cognoscere "to know, to become well-acquainted with," from com- "with" (see com-) + gnoscere "recognize" (see notice (v.)).
Connor: masc. proper name, little used in U.S. before 1980; in the top 100 names given to boys from 1992; apparently an alteration and appropriation of the surname Conner (13c.), representing Old English cunnere "examiner, inspector" (e.g. ale-conner (see con (n.2)).
connotate (v.): 1590s, from Medieval Latin connotatus, past participle of connotare (see connote). Obsolete; replaced by connote.
connotation (n.): 1530s, from Medieval Latin connotationem (nominative connotatio), from connotat-, past participle stem of connotare "signify in addition to the main meaning," a term in logic, literally "to mark along with," from Latin com- "together" (see com-) + notare "to mark" (see note).

A word denotes its primary meaning, its barest adequate definition -- father denotes "one that has begotten." A word connotes the attributes commonly associated with it -- father connotes "male sex, prior existence, greater experience, affection, guidance."
connote (v.): 1660s, from Medieval Latin connotare "to mark along with," (see connotation). A common word in medieval logic. Related: Connoted; connoting.
connubial (adj.): 1650s, from Latin connubialis, variant of conubialis "pertaining to wedlock," from conubium "marriage," from com- "together" (see com-) + nubere "to wed" (see nuptial).
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.