neofunctionalization

This term is a highly specialized technical descriptor used almost exclusively within evolutionary biology and genetics. It describes a specific outcome of gene duplication where the selective pressure on one copy is relaxed, permitting the accumulation of mutations that lead to a novel biological role.

Because it refers to a specific biological process, it is treated as an uncountable noun. It is typically used in academic papers or textbooks to contrast with subfunctionalization, where the original functions are split between the two duplicated genes rather than a new function being created.