mare liberum

noun

ma·​re li·​be·​rum ˈmär-(ˌ)ā-ˈlē-bə-ˌru̇m 

1

: a navigable body of water (such as a sea) that is open to all nations

2

: freedom of the seas

Word History

Etymology

New Latin, literally, free sea

First Known Use

1652, in the meaning defined at sense 1