(1) (Network-to-Network Interface) In ATM networking, the interface between two ATM devices (typically ATM switches). In frame relay networking, the interface between two separate frame relay networks. Contrast with UNI.

(2) (National Nanotechnology Initiative) A U.S. government program designed to accelerate R&D in the nanotechnology field. It was announced in 1999 by President Clinton. The government's NNI budget request for FY 2008 was $1.5 billion. For more information, visit www.nano.gov. See nanotechnology.