An intranet is a restricted-access or internal network that works like the Internet. It enables employees or those with access to browse or share resources.
A much cooler way to say internet, just like saying Canadia instead of Canada. Even if you mean to use it as singular, you must have an "s" at the end of it.
(pl.) Intranet: A closed form of the internet common in workplaces and education centres; essentially a LAN with limited access to internet pages stored on a local database.