area of undeveloped land usually used for recreation.

Land that is partly or wholly a natural environment, e.g. grass, trees, shrubs, or other vegetation. Typically, green assets include fields, parks, woodlands, gardens, orchards, allotments and cemeteries.

A plot of vegetated land separating or surrounding areas of intensive residential or industrial use and devoted primarily to recreational or park uses. (source -EEA Glossary of key terms)