[SSJup81]

Beast
Biisuto (ビースト): This just says "beast" in Katakana
Yajyuu (野獣): This one means the type of beast like a wild animal or monster.
Moujyuu (猛獣): This one means the type of beast like a beast of prey.

Life beneath the streets
Seimei wa michi no shita ni arimasu.
生命は道の下にあります。

Wild
Wairudo (ワイルド): This is just "wild" in Katakana. It's a na-adjective.
Yasei (野性): This means "wild", but as a noun.
Sobou (粗暴): This means wild as in "violent". This is also a na-adjective.

I guess this is what you meant and I can only assume my sentence is right... I'd definitely have someone check this stuff out.