Relating to or characterized by reversion to something ancient or ancestral. His atavistic fear of the dark seemed out of place in the modern world.
Exhibiting traits or behaviors that are reminiscent of a distant ancestor. The atavistic design of the building reminded visitors of ancient Roman architecture.
Primitive or instinctive in a way that recalls humanity’s early ancestors; relating to basic, raw urges or feelings. He felt an atavistic urge to protect his territory at any cost.