Short for "primitivist".
Primitivists have attached themselves to the anarchist movement, and use many of the major journals to warn "Leftists" of an inevitable ecological catastrophe that will kill 90% of humanity, and ensure the remaining 10% can live happily, cave-man stylee, without the fascist constraits of agriculture, language, and so on.
They recognise that real freedom is, evidently, nasty, brutish, and short.

A pre-mature born person