"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.