repressor
/ˈriːprɛsər/Definitions
1. noun
A gene or protein that inhibits the expression of another gene, especially by binding to a regulatory DNA sequence
“The repressor proteins in the bacteria are responsible for preventing the expression of certain virulence factors.”
2. noun
A person or thing that represses or suppresses something
“The government was seen as a repressor of free speech during the time of martial law.”