Superlative form of steep: most steep. Being steep to the greatest degree.(adjective)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "steepest" in a sentence
"The track, about 1,500 yards long for men's luge races, has slopes as steep as 20 degrees and a vertical drop of 498 feet, which the promotional material called the steepest of the world's 15 international competition sliding venues."
"The longest slide was 450 meters, and the steepest was a 20 percent grade."
"• The International Monetary Fund predicted that Britain's recession will be the 'steepest' of leading Western economies;"