What does 颠簸 (diānbǒ) mean in English?

Card 569HSK Level 4569/3571
CARD569
PROGRESS16%
颠簸
顛簸
diānbǒ
bump; welter(Verb)

Reveal: Click/Space/Enter/↑↓/w/s/j/kNavigate: ←→/h/l/a/d