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
* 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|nearest neighbor method for determining the thermodynamics of nucleic acids
* The Single-linkage clustering|nearest neighbor method for calculating distances between clusters in hierarchical clustering.