Nanosciences and nanotechnologies come into a pre-existing legal system. Their arrival, and how they are received are worthy of analysis. Such an effort shall at first include simply lexical considerations, in order to penetrate, via their origins, the traces of these specific objects into the territory of law. The goal of this article is to explore the effects of "nanos" in various legal fields, including their relevance to the principle of precaution, patent law, and the applicable laws for chemical substances.