bash-hackers-wiki/docs/dict/special_file.md

Special file

Unlike a regular file (a bunch of accessible data organized on a filesystem), it's a special filename that points to a ressource or similar:

• character special files
• block special files
• named pipes
• socket files

Since a directory also is only a file, you can count it as special file, too.

See also

• file
• filename
• directory