Noun | 1. | single nucleotide polymorphism - (genetics) genetic variation in a DNA sequence that occurs when a single nucleotide in a genome is altered; SNPs are usually considered to be point mutations that have been evolutionarily successful enough to recur in a significant proportion of the population of a species genetic science, genetics - the branch of biology that studies heredity and variation in organisms polymorphism - (genetics) the genetic variation within a population that natural selection can operate on |