on or onto the shore, the bottom, a reef, etc.: the ship ran aground
- Onto or on a shore, reef, or the bottom of a body of water: a ship that ran aground; a ship aground offshore.
- On the ground: combat aircraft aloft and aground.
- (nautical, of a normally floating craft) Resting on the bottom.
From Middle English agrounde, on grounde (“on ground”), equivalent to a- + ground.