Definitions

1. verb

to wear down or erode (a rock or hill) by the action of water or ice

“The river aggraded the rock over thousands of years.”

2. verb

in geology, to deposit sediment or alluvium (in a river, lake, or sea) as a result of erosion or sedimentation

“The delta is an area where the river has aggraded over time.”

3. noun

in geology, a deposit of sediment or alluvium formed by the action of a river or other watercourse

“The aggrade formed a new coastline along the river delta.”