What is Banishment?

Legal Definition
Crim. law. A punishment inflicted upon criminals, by compelling them to quit a city, place, or country, for, a specified period of time, or for life. Vide 4 Dall. 14. Deportation; Relegation.
-- Bouviers Law Dictionary
Legal Definition
In criminal law. A punishment inflicted upon criminals, by compelling them to quit a city, place or country for a specified period of time or for life. See Cooper v. Telfair, 4 Dali. 14, 1 In Ed. 721; People v. Potter, 1 Park. Cr. R. (N. Y.) 54. It is inflicted principally upon political offenders,1 "transportation" being the word used to express a similar punishment of ordinary criminals. Banishment, however, merely forbids the return of the person banished before the expiration of the sentence, while transportation involves the idea of deprivation of liberty after the convict arrives at the place to which he has been carried. Rap. & L.
-- Black's Law Dictionary
Legal Definition
Removal from the country as a punishment for crime.
-- Ballentine's Law Dictionary