Definition of down preposition from the Oxford Advanced American Dictionary

Oxford3000

down

preposition
/daʊn/
 
 
1 from a high or higher point on something to a lower oneThe stone rolled down the hill.Tears ran down her face.Her hair hung down her back to her waist.2 along; toward the direction in which you are facingHe lives just down the street.Go down the road till you reach the traffic lights.There's a bridge a mile down the river from here.3 all through a period of timean exhibition of costumes down the ages (= from all periods of history)