Definition of "troglodyte"

A member of a supposed prehistoric race that lived in caves or holes, a caveman.  examples

(by extension) Anything that lives underground.  examples

A reclusive, reactionary or out-of-date person, especially if brutish.  examples

The Eurasian wren, Troglodytes troglodytes.  examples

(computing) A person who chooses not to keep up-to-date with the latest software and hardware.  examples