Public open space

Public open space is often referred to by urban planners and landscape architects by the acronym 'POS'. Varied interpretations of the term are possible.
'Public' can mean:

owned by a national or local government body
owned by 'public' body and held in trust for the public
owned by a private individual or organization but made available for public use or available public access, see privately owned public space

'Open' can mean:

open for public access
open for public recreation
outdoors, i.e. not a space within a building
vegetated

Depending on which of these definitions are adopted, any of the following could be called Public Open Space:

a public park
a town square
a greenway which is open to the public but runs through farmland or a forest
a public highway
a private road with public access