He plunged down the steep slope on his bike and broke into a cold sweat.
Tips
usage
陡 ('steep') as a stand-alone adjective is common, but the noun is usually 陡坡 — a fixed compound. You see it on Chinese road signs as 注意陡坡 ('caution: steep slope') and in hiking/cycling contexts. Compare 缓坡 (huǎnpō, 'gentle slope') as the antonym.
