"to study, get to know, peruse carefully," c. 1200, cunnen, "make an attempt, try or seek to do," from Old English cunnian "to know" (see can (v.1)). Related: Conned; conning.
"swindling," 1889 (in con man), 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 artist is attested by 1910.
"to guide a ship, give orders for the steering of a ship," 1620s, from French conduire "to conduct, lead, guide" (10c.), from Latin conducere "to lead or bring together, contribute, serve," from com "with, together" (see com-) + ducere "to lead" (from PIE root *deuk- "to lead"). As a noun, "action or post of steering a ship," 1825. Related: Conned; conning. Conning tower "dome-shaped pilot house of an ironclad warship or submarine" is attested from 1865.
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.
abbreviation of Latin phrase nemine contradicente "no one dissenting," hence, "without opposition." From ablative of nemo "nobody" + ablative present participle of contradicere.