The word "颠簸" is formed by combining the characters "颠" and "簸", each contributing related meanings of shaking or instability. "颠" denotes jolting or falling, often linked to the head or top, and "簸" refers to winnowing or tossing, involving back-and-forth movement. Their conjunction creates a compound word that specifically describes a bumpy or rough motion, as in traveling over uneven surfaces.