An epistatic gene is a gene that can alter or mask the expression of another gene's phenotype. Synonyms for the term epistatic gene include controlling gene, inhibitory gene, regulatory gene, dominant gene, and masking gene. These genes interact with other genes in the genome and can affect various aspects of an organism's traits and characteristics, including morphology, physiology, and behavior. Epistasis can have significant impacts in evolutionary biology and genetic inheritance. The identification and characterization of these genes are crucial for understanding gene interactions and the genetic basis of complex traits in organisms.