0 abbreviation for Site of Special Scientific Interest: in the UK, a place that is officially protected because it has important or rare animals, plants, geology (= rocks and land forms), etc.:
The landowner was opposed to part of his land being designated an SSSI.
As an SSSI and a national nature reserve, the coastal area is of international environmental importance.
After consultation with the Nature Conservancy Council for Scotland (the glen is an SSSI), we will mark and repair footpaths.
an application for quarrying on the Carmel Woods SSSI