Other forms: sandbars
A sandbar is a ridge of sand built up in shallow water. Ground on a sandbar, a shifting sandbar, the sandbar at the mouth.
They form where a current slows and drops what it carries, which is why river mouths have them, and they move, so a chart can be out of date within a season. Many harbours were unusable at low water because of one.
1nounsandbarA ridge of sand built up in shallow water.
“At low tide we walked out along the sandbar to the little island.”
sandbar is a ridge.
Sand plus bar, from bar in the sense of a barrier across a channel.
From sand + bar.
Etymology from Wiktionary, CC BY-SA