con (n.1)youdaoicibaDictYouDict[con 词源字典]
"negation" (mainly in pro and con), 1570s, short for Latin contra "against" (see contra).[con etymology, con origin, 英语词源]
con (n.2)youdaoicibaDictYouDict
"study," early 15c., from Old English cunnan "to know, know how" (see can (v.1)).
con (adj.)youdaoicibaDictYouDict
"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)youdaoicibaDictYouDict
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)youdaoicibaDictYouDict
"to guide ships," 1620s, from French conduire "to conduct, lead, guide" (10c.), from Latin conducere (see conduce). Related: Conned; conning.
con (v.2)youdaoicibaDictYouDict
"to swindle," 1896, from con (adj.). Related: Conned; conning.