Yeah, it's a good one to pull-out.
If I could rewind the clock (and, er, was smarter/more attentive), I'd love to be an IP lawyer. Fascinating field imo.
You can trademark any word - or can try - but only to a specific category (or 'class') of goods or services.
It's why an Oasis band, drink and clothes shop all co-existed happily.
Invincibles has presumably been registered in the fields of sports merch and events.
That doesn't stop anyone...