Ranger
Part of speech: noun
Definition: a keeper, guardian, or soldier who ranges over a region to protect the area or enforce the law.
Example sentence: I weren't an actor, I'd be a wildlife biologist or forest ranger.
Commando
Part of speech: noun
Definition: A small fighting force specially trained for making quick destructive raids against enemy-held areasA commando trooperAn organized force of Boer troops in South Africa; a raid by such troops