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to pile up; to stack
to load (car, ship, etc.); to pack
to acquire; to accumulate
経験を積むことが成長につながると思う。
I think gaining experience leads to growth.
トラックに荷物を積んで運搬を始めた。
I loaded the cargo onto the truck and started transporting.
本を机の上に高く積んで読む準備をした。
I piled books high on the desk and prepared to read.