The Precautionary Principle is a strategy to cope with possible risks where scientific understanding is yet incomplete, such as the risks of nano technology, genetically modified organisms and systemic insecticides. A precaution is a careful action you make in advance. You might want to take theprecaution of bringing lots of water and sunblock if you're going on a desert hike.Precaution means exactly what it sounds like. The prefix pre- means before, and caution means carefulness in the face of danger.