noun
A wooden or metal stake driven into the ground, used for marking boundaries, supporting structures, or as a foundation pile.
工事現場に棒杭が何本も打ち込まれていた。
Several stakes had been driven into the ground at the construction site.
境界を示すために棒杭を立てた。
We put up stakes to mark the boundary.
杭 is a general term for a stake or pile; 棒杭 specifically emphasizes a straight, rod-like stake.
Compound of 棒 (bō, 'rod, pole') and 杭 (kui, 'stake, pile'). The reading ぼうぐい is a straightforward combination.