Play hardball

To play hardball is to act in a ruthless and uncompromising way, an American colloquialism that dates from the late 19th century and derives from baseball, which uses a hardball to distinguish it from softball. Softball is a less rigorous form of baseball that uses a larger, softer ball and was invented in 1887 as a game that could be played indoors and was designed to be more suitable for women and children. Children, of course, would start with softball but would aspire to ‘play hardball’, which gave this figurative usage added impetus.