footboard; gangplank; scaffolding board
A board used as a temporary walkway, such as a plank for boarding a ship, crossing a gap, or walking on scaffolding.
I crossed the gangplank to board the ship.
I walked carefully on the scaffolding board at the construction site.
Compound of 歩み (ayumi, 'walking') + 板 (ita, 'board'). The reading あゆみいた is a straightforward combination of the kun'yomi readings of the two kanji.