beat it!; get lost!; get out of my sight!
Rough, blunt imperative from the verb 失せる (to disappear, to go away). Used in anger or strong dismissal, often in masculine or tough speech. Equivalent to telling someone to scram or buzz off.
See also: 失せる
Get lost! Don't ever show your face again.
Beat it, you bastard!
get lost; go away; scram
Imperative form of the verb 失せる (うせる), which historically meant 'to disappear' or 'to die'. The interjection developed from the blunt command to go away or vanish.