OUTRUNNER

a person who or animal which runs along the outside or outer side of something, as an attendant who runs ahead of or beside a carriage, a dog leading a team of sledge dogs, etc. also figurative: one who goes about gathering or spreading intelligence; a forerunner, an advance party (now chiefly historical).

a projection or outshoot of a forest, mountain range, or some other physical feature.

a person who or thing which outruns something.