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 (e.g. a not-for-profit organization) 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 (POPS)
'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