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trail - n. a path through a forest, field, etc.
Apache - n. a member of a Native American people of the southwestern U.S.
flee - v. to run away from danger (Irregular past tense: fled)
gravity - n. the natural force that tends to cause physical things to move towards each other : the force that causes things to fall towards the Earth
Martian - n. an imaginary creature in books, movies, etc., that lives on or comes from the planet Mars
