Nearest neighbor may refer to:

• Nearest neighbor search in pattern recognition and in computational geometry
• Nearest-neighbor interpolation for interpolating data
• Nearest neighbor graph in geometry
• Nearest neighbor function in probability theory
• Nearest neighbor decoding in coding theory
• The k-nearest neighbor algorithm in machine learning, an application of generalized forms of nearest neighbor search and interpolation
• The nearest neighbour algorithm for approximately solving the travelling salesman problem
• The nearest-neighbor thermodynamic parameters for determining the thermodynamics of nucleic acids
• The nearest neighbor clustering for calculating distances between clusters in hierarchical clustering

• Moore neighborhood
• Von Neumann neighborhood