meaning

Basically, an emerging field of science and technology which deals with machines and robots having sizes in nanometres. A nanometre is defined to be 1/1,00,00,00,000 of a metre, particles so small that they can't be identified or observed without the use of a sophisticated microscope. 

The applications range from healthcare to repair of machinery. Imagine small blood cell sized robots going inside the body and repairing damaged blood vessels and curing cancer, we'll probably be seeing a lot of this in the next 20-30 years or so . It's already a billion dollar industry and will expand in size. 

Tennis balls are one good example of the use of nanotechnology, so is the wrinkle free and water resistant cloth that's coming in the market. Google up for more information.