/usr stands for ‘user’. In particular, in our own version of the system, there is a directory "/usr" which contains all user's directories, and which is stored

/usr stands for ‘user’. In particular, in our own version of the system, there is a directory "/usr" which contains all user's directories, and which is stored on a relatively large, but slow moving head disk, while the othe files are on the fast but small fixed-head disk. — https://www.bell-labs.com/usr/dmr/www/notes.html https://www.bell-labs.com/usr/dmr/www/notes.html