Nanotechnology is the branch of technology that deals with dimensions and tolerances of 1 to 100 nanometres, or, generally, with the manipulation of individual atoms and molecules.
First uses of the word nanotechnology:
1974 N. TANIGUCHI in Proc. Internat. Conf. Production Engin. II. 18/1 The usual precision finishing technology has aimed to get the preciseness and fineness of 1 m, i.e. 10-6m in length, hence it says ‘micro-technology’, not so accurate in meaning. Consequently, in contrast, the finishing technology aimed to get the preciseness and fineness of 1nm would be called ‘Nano-technology’. 1986 K. E. DREXLER Engines of Creation i. 11 As nanotechnology moves beyond reliance on proteins, it will grow more ordinary from an engineer's point of view.
1998 Independent 2 Apr. 2/7 The most obvious use for such a power plant would be in ‘nanotechnology’ systems, where mechanical systems may be so tiny that hundreds of them can fit onto the head of a pin. 2000 Business Rev. Weekly 11 Aug. 60 The areas that some venture capitalists are entering include biotechnology, and ‘over the horizon’ developments such as micro-machining and nanotechnology.
(From the Oxford English Dictionary Online)