- con (n.1)
- "negation" (mainly in pro and con), 1570s, short for Latin contra "against" (see contra).
- con (n.2)
- "study," early 15c., from Old English cunnan "to know, know how" (see can (v.1)).
- con (adj.)
- "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)
- a slang or colloquial shortening of various nouns beginning in con-, e.g., from the 19th century, confidant, conundrum, conformist, convict, contract, and from the 20th century, conductor, conservative.
- con (v.1)
- "to guide ships," 1620s, from French conduire "to conduct, lead, guide" (10c.), from Latin conducere (see conduce). Related: Conned; conning.
- con (v.2)
- "to swindle," 1896, from con (adj.). Related: Conned; conning.