con (n.1) Look up con at Dictionary.com
"negation" (mainly in pro and con), 1570s, short for Latin contra "against" (see contra).
con (n.2) Look up con at Dictionary.com
"study," early 15c., from Old English cunnan "to know, know how" (see can (v.1)).
con (adj.) Look up con at Dictionary.com
"swindling," 1889, American English, from confidence man (1849), from the many scams in which the victim is induced to hand over money as a token of confidence. Confidence with a sense of "assurance based on insufficient grounds" dates from 1590s.
con (n.3) Look up con at Dictionary.com
a slang or colloquial shortening of various nouns beginning in con-, such as, from the 19th century, confidant, conundrum, conformist, convict, contract, and from the 20th century, conductor, conservative.
con (v.1) Look up con at Dictionary.com
"to guide ships," 1620s, from French conduire "to conduct, lead, guide" (10c.), from Latin conducere (see conduce). Related: Conned; conning.
con (v.2) Look up con at Dictionary.com
"to swindle," 1896, from con (adj.). Related: Conned; conning.
con- Look up con- at Dictionary.com
word-forming element meaning "together, with," sometimes merely intensive; the form of com- used in Latin before consonants except -b-, -p-, -l-, -m-, or -r-. In native English formations (such as costar), co- tends to be used where Latin would use con-.
conation (n.) Look up conation at Dictionary.com
in philosophical use from 1836, from Latin conationem (nominative conatio) "an endeavoring, effort," noun of action from past participle stem of conari "to endeavor, to try," from PIE *kona-, from root *ken- (1) "to set oneself in motion" (see deacon).
conative (adj.) Look up conative at Dictionary.com
1836, from Latin conat-, past participle stem of conari "to endeavor, to try" (see conation) + -ive.
concatenate (v.) Look up concatenate at Dictionary.com
c.1600, from Late Latin concatenatus, past participle of concatenare "to link together" (see concatenation). Related: Concatenated; concatenating.
concatenation (n.) Look up concatenation at Dictionary.com
c.1600, from Late Latin concatenationem (nominative concatenatio) "a linking together," noun of action from past participle stem of concatenare "to link together," from com- "together" (see com-) + catenare, from catena "a chain" (see chain (n.)).
concave (adj.) Look up concave at Dictionary.com
early 15c., from Old French concave (14c.) or directly from Latin concavus "hollow, arched, vaulted, curved," from com-, intensive prefix (see com-), + cavus "hollow" (see cave (n.)).
concavity (n.) Look up concavity at Dictionary.com
c.1400, from Old French concavité "hollow, concavity" (14c.) or directly from Latin concavitatem (nominative concavitas), from Latin concavus "hollow" (see concave).
conceal (v.) Look up conceal at Dictionary.com
early 14c., concelen, from Old French conceler "to hide, conceal, dissimulate," from Latin concelare "to hide," from com-, intensive prefix (see com-), + celare "to hide," from PIE root *kel- (2) "to cover, conceal" (see cell). Replaced Old English deagan. Related: Concealed; concealing.
concealment (n.) Look up concealment at Dictionary.com
early 14c. (late 13c. in Anglo-French), from Old French concelement "concealment, secrecy," from conceler "to hide" (see conceal). Originally a term in law; general sense is from c.1600.
concede (v.) Look up concede at Dictionary.com
1630s, from Middle French concéder or directly from Latin concedere "give way, yield, go away, depart, retire," figuratively "agree, consent, give precedence," from com-, intensive prefix (see com-), + cedere "to go, grant, give way" (see cede). Related: Conceded; conceding.
conceit (n.) Look up conceit at Dictionary.com
late 14c., "something formed in the mind, thought, notion," from conceiven (see conceive) based on analogy of deceit and receipt. Sense evolved from "something formed in the mind," to "fanciful or witty notion" (1510s), to "vanity" (c.1600) through shortening of self-conceit (1580s).
conceited (adj.) Look up conceited at Dictionary.com
c.1600, "having an overweening opinion of oneself" (short for self-conceited, 1590s); earlier "having intelligence" (1540s); past participle adjective from conceit (q.v.).
conceivable (adj.) Look up conceivable at Dictionary.com
mid-15c. (implied in conceivableness), from conceive + -able. Originally in a now-obsolete sense "that can be received." Meaning "that can be imagined" is attested from 1620s (in conceivably).
conceive (v.) Look up conceive at Dictionary.com
late 13c., conceiven, "take (seed) into the womb, become pregnant," from stem of Old French conceveir (Modern French concevoir), from Latin concipere (past participle conceptus) "to take in and hold; become pregnant," from com-, intensive prefix (see com-), + comb. form of capere "to take," from PIE *kap- "to grasp" (see capable). Meaning "take into the mind" is from mid-14c., a figurative sense also found in the Old French and Latin words. Related: Conceived; conceiving.
concent (n.) Look up concent at Dictionary.com
"harmony," 1580s, from Latin concentus "a singing together, harmony," from concinere "to sing or sound together," from com- "with, together" (see com-) + canere "to sing" (see chant (v.)). Often misspelled consent or confused with that word.
concentrate (v.) Look up concentrate at Dictionary.com
1630s, "to bring or come to a common center," from concenter (1590s), from Italian concentrare, from Latin com- "together" (see com-) + centrum "center" (see center (n.)). Meaning "condense" is from 1680s. Sense of "mentally focus" is c.1860. Related: Concentrated; concentrating.
concentrate (n.) Look up concentrate at Dictionary.com
1883, from concentrate (v.).
concentration (n.) Look up concentration at Dictionary.com
1630s, "action of bringing to a center," noun of action from verb concentrate (v.). Meaning "a mass so collected" is from 1670s; "continuous focus of mental activity" is from 1846.
concentration camp (n.) Look up concentration camp at Dictionary.com
1901, "compound for noncombatants in a war zone" (see concentration); a term for a controversial idea in the second Boer War (1899-1902), and the term emerged with a bad odor.
The concentration camp now definitely taken its place side by side with Black Hole of Calcutta as one of those of horror at which humanity will never cease shudder. ["The Review of Reviews," London, March 1902]
It also was used 1902 in reference to then-current U.S. policies in the Philippines, and retroactively in reference to Spanish policies in Cuba during the insurrection there of 1896-98. The phrase was used in U.S. during the Spanish-American war, but in reference to designated rendezvous points for U.S. troops headed overseas. In reference to prisons for dissidents and minorities in Nazi Germany from 1934, in Soviet Russia from 1935.
concentric (adj.) Look up concentric at Dictionary.com
c.1400, from Middle French concentrique, from Medieval Latin concentricus, from com- "together" (see com-) + centrum "circle, center" (see center (n.)).
concept (n.) Look up concept at Dictionary.com
1550s, from Medieval Latin conceptum "draft, abstract," in classical Latin "(a thing) conceived," from concep-, past participle stem of concipere "to take in" (see conceive). In some 16c. cases a refashioning of conceit (perhaps to avoid negative connotations).
conception (n.) Look up conception at Dictionary.com
early 14c., "act of conceiving," from Old French concepcion (Modern French conception) "conception, grasp, comprehension," from Latin conceptionem (nominative conceptio) "a comprehending, conception," noun of action from stem of concipere (see conceive). Originally in the womb sense (also with reference to Conception Day in the Church calendar); mental sense "process of forming concepts" is late 14c. Meaning "that which is conceived in the mind" is from 1520s; "general notion" is from 1785.
conceptive (adj.) Look up conceptive at Dictionary.com
1630s, from Latin conceptivus, from conceptus, past participle of concipere (see conceive).
conceptual (adj.) Look up conceptual at Dictionary.com
1820, "pertaining to mental conception" (there is an isolated use from 1662), from Medieval Latin conceptualis, from Latin conceptus "a collecting, gathering, conceiving," past participle of concipere (see conceive). Related: Conceptualism; conceptualist.
conceptualisation (n.) Look up conceptualisation at Dictionary.com
chiefly British English spelling of conceptualization; for spelling, see -ize.
conceptualise (v.) Look up conceptualise at Dictionary.com
chiefly British English spelling of conceptualize; for suffix, see -ize. Related: Conceptualised; conceptualising.
conceptualization (n.) Look up conceptualization at Dictionary.com
1866; see conceptual + -ization. Perhaps based on French conceptualisation (1862).
conceptualize (v.) Look up conceptualize at Dictionary.com
1892, from conceptual + -ize. Related: Conceptualized; conceptualizing.
conceptually (adv.) Look up conceptually at Dictionary.com
1842, from conceptual + -ly (2).
concern (v.) Look up concern at Dictionary.com
early 15c., "perceive, distinguish," also "refer to, relate to," from Middle French concerner, from Medieval Latin concernere "concern, touch, belong to," figurative use of Late Latin concernere "to sift, mix, as in a sieve," from Latin com- "with" (see com-) + cernere "to sift," hence "perceive, comprehend" (see crisis). Apparently the sense of the prefix shifted to intensive in Medieval Latin. Meaning "worry" is 17c. Related: Concerned; concerning. Letter opening to whom it may concern attested by 1740.
concern (n.) Look up concern at Dictionary.com
1580s, from concern (v.).
concert (n.) Look up concert at Dictionary.com
1660s, "agreement, accord, harmony," from French concert (16c.), from Italian concerto "concert, harmony," from concertare "bring into agreement," in Latin "to contend, contest, dispute," from com- "with" (see com-) + certare "to contend, strive," frequentative of certus, variant past participle of cernere "separate, decide" (see crisis).

Before the word entered English, meaning shifted from "to strive against" to "to strive alongside." Sense of "public musical performance" is 1680s. But Klein considers this too much of a stretch and suggests Latin concentare "to sing together" (from con- + cantare "to sing") as the source of the Italian word in the musical sense.
concertina (n.) Look up concertina at Dictionary.com
1835, from concert + fem. ending -ina. Portable musical instrument invented 1829 by Sir Charles Wheatstone. Concertina wire attested by 1917, so called from similarity to the musical instrument.
concerto (n.) Look up concerto at Dictionary.com
1730, from Italian concerto (see concert). Concerto grosso is from 1724.
concession (n.) Look up concession at Dictionary.com
mid-15c., from Old French concession (14c.) or directly from Latin concessionem (nominative concessio) "an allowing, conceding," noun of action from past participle stem of concedere (see concede). Meaning "right or privilege granted by government" is from 1650s. "Refreshment stand" sense is from 1910.
concessionaire (n.) Look up concessionaire at Dictionary.com
1862, from French concessionaire "person to whom a concession has been granted," from concession, from Latin concessionem (see concession).
conch (n.) Look up conch at Dictionary.com
type of shell, early 15c., from Latin concha "shellfish, mollusk," from Greek konkhe "mussel, shell," from PIE root *konkho-. The name for natives of Florida Keys since at least 1833; the prefered pronunciation there ("kongk") preserves the classical one.
concierge (n.) Look up concierge at Dictionary.com
1640s, from French concierge "caretaker, doorkeeper, porter" (12c.), probably from Vulgar Latin *conservius, from Latin conservus "fellow slave," from com- "with" (see com-) + servius "slave" (see serve (v.)).
conciliate (v.) Look up conciliate at Dictionary.com
1540s, from Latin conciliatus, past participle of conciliare "to bring together, unite in feelings, make friendly," from concilium "council" (see council). Related: Conciliated; conciliating.
conciliation (n.) Look up conciliation at Dictionary.com
1540s, from Middle French conciliation, from Latin conciliationem (nominative conciliatio) "a connection, union, bond," figuratively "a making friendly, gaining over," noun of action from past participle stem of conciliare (see conciliate).
conciliatory (adj.) Look up conciliatory at Dictionary.com
1570s, from conciliate + -ory. Related: Conciliator.
concise (adj.) Look up concise at Dictionary.com
1580s, from Latin concisus "cut off, brief," past participle of concidere "to cut off, cut up, cut through, cut to pieces," from com-, intensive prefix (see com-), + caedere "to cut" (see -cide). Related: Concisely.
conciseness (n.) Look up conciseness at Dictionary.com
"expression of much in few words," 1650s, from concise + -ness.
[Conciseness] is the English word familiar to the ordinary man: concision is the LITERARY CRITIC'S WORD, more recent in English, used by writers under French influence & often requiring the reader to stop & think whether he knows its meaning. [Fowler]
concision (n.) Look up concision at Dictionary.com
late 14c., "cutting away, mutilation," also, from 16c., "circumcision," from Latin concisionem "a separation into divisions," literally "a cutting up," noun of action from past participle stem of concidere "to cut up" (see concise). From 18c. it began to be used in the sense of conciseness (q.v.).