NNS can stand for:
New neoclassical synthesis (economics)
NASCAR Nationwide Series (previous name of the NASCAR Xfinity Series)
Nashville Number System (music)
National Numeracy Strategy (UK education)
Near Net Shape
Nearest neighbor search
Nearly-new sale
Newport News Shipbuilding, a shipyard
Nigerian Navy Ship
Nippon Television Network System
Non-Nutritive Sweetener, i.e.