Entry 1 sense Webster, 1913 Sea rover /sē rōv'-ẽr/ · Sea· rov·er · IPA 01 One that cruises or roves the sea for plunder; a sea robber; a pirate; also, a piratical vessel. 1. One that cruises or roves the sea for plunder; a sea robber; a pirate; also, a piratical vessel.