deregulatory UK /diːˈɹɛɡjələtɹi/US /diːˈɹɛɡjulətɔɹi/ adjective1 •Of or pertaining to deregulation.Speaking at the White House Thursday, the president called the elimination of the finding the "single largest deregulatory action in American history." — 2026 formsmore deregulatory · most deregulatory