/ ˈflæʃə(r); NAmE / noun
1.
( informal ) a man who shows his sexual organs in public, especially in order to shock or frighten women
2.
a device that turns a light on and off quickly
3.
( NAmE ) a light on a vehicle that you can turn on and off quickly as a signal :
four-way flashers (= four lights that flash together to warn other drivers of possible danger)