Definitions of uphill:

• noun:   the upward slope of a hill
• adjective:   hard to overcome or surmount

  Example: "An uphill battle against a popular incumbant"

• adjective:   sloping upward
• adverb:   upward on a hill or incline

  Example: "This street lay uphill"

• adverb:   against difficulties

  Example: "She was talking uphill"