Originally meant "warlike" or "aggressive." Now means "drunk" due to
widespread misuse. But that's the idea behind
urban words, so now it means drunk.
(Original) Archibald has been
ruffling this
fellow's feathers for nearly a fortnight now.
I dare say he has been simply belligerent.
(Modern) Oh my gawd this muff cabbage pissed awl over Johnny B's carpet. What a belligerent bitch.