Perpetrator of unearthly wailing that is much feared in Ireland and western Scotland as an omen of approaching death. The banshee is usually heard at night around 2 a.m. and its supernatural ululations are generally associated with a particular family or clan, who can often detail a history of such warnings from spectral (usually female) guardiens. Examples of famous banshees include the one linked to the aristocratic Rossmore family of Country Monaghan in Ireland, which was first heard in 1801 and has heralded the death of each successive heir to the baronetcy (including that of the sixth baronet in 1958).
Some claim that the banshee wail is made by the fairies who sense the coming of death and want to warn the family (bean si in Gaelic means 'fairy woman'). Alternatively the banshee is held to be a dead ancestor or perhaps the vengeful spirit of a woman who has suffered some wrong at the family's hands. In some parts of Scotland the banshee is known as the 'washer by the ford' because her figure is seen washing the bloodstained clothes of the person fated to die. Sometimes the banshee is not in the form of a voice but is heard as a beating drum.
There are a few notable ways to foresee a banshee's coming. One, in Ireland, is to find a comb upon the ground, or a stack of rocks in your path.  A few ways are known to ward off the banshee, one is by holding a sword to the 'spirit' during her visit. This entraps her in your command, and you can send her on her way. Another is to NEVER pick up the comb that you find, as this is the banshees way of luring(although, most of the time this gives just enough foresight to be cautious of her arrival).