accumulate, tired

累 is composed of the simplified form of 畾 (pile, thunder) and the radical of 糸 (silk, thread). 畾 depicts three wheels, and because its form resembles a small mound or pile, it conveys the idea of piling up or stacking. 糸 depicts a bundle of silk threads bound together and carries the idea of entanglement or winding around. When anyone is entangled and weighed down by burdens piled up like a mountain, one will inevitably feel exhausted.