She sat talking in low murmurs with Selden, and turning a contemptuous and denuded shoulder toward her host, who, far from resenting his exclusion, plunged into the excesses of the MENU with the joyous irresponsibility of a free man.
Even the most irresponsible pretty woman of her acquaintance had her inherited obligations, her conventional benevolences, her share in the working of the great civic machine; and all hung together in the solidarity of these traditional functions.
There are no more uses of "irresponsible" in the book.
Show samples from other sources
After much passing around of money Cousin Joshua was moved across the tracks and placed in state accommodations for the irresponsible, where he remained for the rest of his days.
Harper Lee -- Go Set a Watchman
"The fact of the matter is, we’ve been irresponsible," Marybeth continues.