IPA: /ˈstiːpən/
KK: /ˈstipən/
To make something have a greater slope or incline.
The workers will steepen the road to improve drainage.
Past: steepened
Past Participle: steepened
Steepen is formed from "steep" (from Old English *stæpe*, meaning high or steep) and "-en" (a suffix used to form verbs indicating to make or become). The word "steepen" means to make something steep or to increase the steepness of a slope.
Think of making something 'high' or 'steep' — 'steep' refers to a high incline, and '-en' means to make it so.