downhill

Adjective

• sloping down rather steeply

Adverb

• toward the bottom of a hill
  • running downhill, he gained a lot of speed
    

• toward a lower or inferior state
  • your performance has been going downhill for a long time now
    

Noun

• a ski race down a trail

• the downward slope of a hill

Related words

• Synonyms: 
  declivitous , downward-sloping