Know how to use "fewer" and "less"? Find out.
"courageous, masculine," 1959, first attested in Norman Mailer (writing of Truman Capote); see balls + -y (2).
Courage; balls, guts: a dangerous ethic of ballsiness in international affairs (1950s+)
Courageous; spunky; gutsy: Angelina Jolie's a very ballsy lady (late 1950s+)