Steep.
Synonyms:
abrupt, high, precipitous, sharp, sheer.
High is used of simple elevation; steep is said only of an incline where the vertical measurement is sufficiently great in proportion to the horizontal to make it difficult of ascent. Steep is relative; an ascent of 100 feet to the mile on a railway is a steep grade; a rise of 500 feet to the mile makes a steep wagon-road; a roof is steep when it makes with the horizontal line an angle of more than 45°. A high mountain may be climbed by a winding road nowhere steep, while a little hill may be accessible only by a steep path. A sharp ascent or descent is one that makes a sudden, decided angle with the plane from which it starts; a sheer ascent or descent is perpendicular, or nearly so; precipitous applies to that which is of the nature of a precipice, and is used especially of a descent; abrupt is as if broken sharply off, and applies to either acclivity or declivity. Compare HIGH.
Antonyms:
easy, flat, gentle, gradual, horizontal, level, low, slight.