A person obsessed with saving the environment to the point of horribly obnoxious smugness.
Envirocunts will quite happily exaggerate or even downright lie about the damage caused to the environment by our modern lifestyles to make a point; will condescend you if you eat a burger from McDonalds; will preach about using energy saving lightbulbs - but conversely they're quite happy to print thousands of hackneyed leaflets that nobody ever reads, eat imported Vegan guff that won't grow in our cold climates to support their 'ethical diet' and spend hours online trying to convince people that they're right. Like most activists then, they're just sanctimonious hypocrites who want something to get indignant about. Absolute cunts.
I went past the university library today and some pinko envirocunt handed me a leaflet about saving energy, eating tofu and 'No war for oil', so I tore it up, put it in the bin and told them 'If you're really that bothered then fish it out and recycle it'.