The Collaborative International Dictionary
Asteism \As"te*ism\, n. [Gr. ? refined and witty talk, fr. ? of the town, polite, witty, fr. ? city: cf. F. ast['e]isme.] (Rhet.) Genteel irony; a polite and ingenious manner of deriding another.
Douglas Harper's Etymology Dictionary
"genteel irony, polite mockery," 1580s, from Greek asteismos "wit, witticism," from asteios "of a city or town" (as opposed to "country"), from asty "town, city," especially (without the article) "Athens."
n. Polite irony; a genteel and ingenious manner of deriding another.