To call a woman and old bat is not to call her an old battle-ax, as many people believe. Bat is not a shortening of battle-ax here, but English slang for a prostitute that goes back to at least 1612. A bat was a prostitute who walked the streets; like a bat she usually worked at night, or, if she worked during the day, she hid out in dark recesses like a bat. To go on a bat, a binge or a drinking spree, is similarly connected with the nocturnal bat – the “night bird,” not the prostitute. Someone who goes on a bat often stays out all night. The first such bat recorded in literature, in 1848, describes the spree as taking place at night. The winged, rodent-like bat was called by the colorful name flittermouse in days past. It figures in many expressions.