The skin on his forehead is a bit bumpy. This is the bumpiest road in the town.
Advanced English Dictionary
+adjective (bumpier, bumpiest) 1 (of a surface) not even; with a lot of bumps: a bumpy road / track + bumpy ground 2 (of a journey) uncomfortable with a lot of sudden unpleasant movements caused by the road surface, weather conditions, etc: a bumpy ride / flight Idioms: have / give sb a bumpy ride to have a difficult time; to make a situation difficult for sb
Random quote: When the solution is simple, God is answering.: Albert Einstein