How to hide that a certain non-WordPress directory exists on the server?

I’m very much a newcomer to WordPress and to this site, so I apologize if this is easy or addressed elsewhere.

I have a WP 4.0 site, using a naked domain, with the WP installation in its own directory /path/public_html/wp. My permalinks are set to use “post name”, so the about page has the address, for example. However if anyone were to type in, they would get my theme’s 404 page.

What I would like is to create a directory /path/public_html/other (note: I don’t have a page in WordPress called “Other”), with permissions 755, but hide the fact of other‘s existence. I want anyone going to to get the normal WordPress 404 page as if this directory didn’t exist at all.

Of course I realize this is not completely foolproof, and I’m aware of the pitfalls of secret URLs, but if you can, please humor me – any help with creating an .htaccess file for this redirection would be appreciated.

An extremely rough approach would be to just paste the 404 page into an index.php file in the other folder, but of course this would not change as the other content of my site changed, eventually falling out of sync and creating a noticable disparity with the “real” 404 page.

Again, any help would be greatly appreciated, and I’m happy to provide any more information about my installation if necessary.

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