Yes, you can password-protect your entire WordPress website using a plugin like Password Protected. Simply install and activate the plugin, then set a password that visitors will need to enter in order to access your website. However, keep in mind that this will make your entire website inaccessible to search engines, so it may not be ideal for SEO purposes. It's also important to remember that password-protecting your entire website can significantly impact user experience, so it's best to only use this option if absolutely necessary.