rover : Idioms & Phrases

• at casual marks; hence, at random; as, shooting at rovers. See def. 5 (a) above. Addison.

  Bound down on every side with many bands because it shall not run at rovers. Robynson (More's Utopia).

Webster 1913

• noun someone who robs at sea or plunders the land from the sea without having a commission from any sovereign nation
  buccaneer; sea robber; pirate.
  

WordNet

Sea" rov"er

Definitions

1. One that cruises or roves the sea for plunder; a sea robber; a pirate; also, a piratical vessel.

Webster 1913