bridge pillar; bridge pile
Refers to the vertical supports driven into the riverbed or ground to hold up a bridge. A technical or descriptive term.
Old bridge pillars remain in the riverbed.
Standard kanji spelling using 杭 (stake/pile).
Rare variant using 杙 (stake); 杭 is more common.
Compound of 橋 (はし, 'bridge') and 杭/杙 (くい, 'stake, pile').