Gene duplication refers to the process by which a gene or a group of genes is copied or duplicated within the genome. It leads to an increase in the number of copies of a specific gene, which can result in altered protein expression. There are several synonyms that can be used to describe gene duplication, including gene multiplication, gene replication, gene copying, gene amplification, gene proliferation, and gene homogenization. These terms all refer to the same phenomenon and are often used interchangeably. Gene duplication plays a critical role in evolution as it contributes to the creation of new genes, and also has implications in disease and genetic disorders.