Sloping upwards refers to an inclination or incline that rises gradually. The antonyms for sloping upwards are sloping downwards or declining. Sloping downwards refers to an inclination or incline that descends gradually, while declining means to gradually decrease in level or quantity. Other antonyms for sloping upwards include flat, level, and horizontal, which indicate a surface that remains at the same height or level. Sloping downwards and declining are often used in business and economics to describe a decrease in market values, sales, or profits. Meanwhile, flat, level, and horizontal are commonly used in architecture, engineering, and construction to describe a surface that is even and balanced.