Make certain words (like city names) unavailable for registration???

Super Admin -> Options.

Scroll down to “banned site names”. Fill ’em in.

tx again multisite maven. Any change to import a .csv/.txt or .php with all the banned names?

found this https://mu.www.ads-software.com/forums/topic/16995

It’s just a space-separated list.

I’d just create the sites myself and use them later on if you wanted to or reassign them to someone if they needed them. Less overhead with database queries.