Anything considered old-fashioned.
A back issue of a magazine, etc.
Anything that lives underground.
A person who chooses not to keep up-to-date with the latest software and hardware.
A reclusive, reactionary or out-of-date person, especially if brutish.
The Eurasian wren, Troglodytes troglodytes.
A member of a supposed prehistoric race that lived in caves or holes, a caveman.