caveman
n. B1 Intermediate US //ˈkeɪvˌmæn// UK //kˈeɪvmən// cave·man
n. a person who lived in the past and used simple tools. It is also a funny way to describe someone who is very old-fashioned or doesn't know much about modern technology.
n. a member of a prehistoric human group, typically associated with the Stone Age. In modern informal contexts, it refers to a person perceived as primitive, unsophisticated, or lacking modern knowledge.
He acts like a real caveman when he doesn't know how to use a computer.
The museum's new exhibit features tools used by early humans, helping visitors understand the life of a caveman.
From cave + man, based on the supposition that early humans dwelt in caves.