A process in which a star gathers molecules of interstellar gas to itself by gravitational attraction.

Artificial buildup of land due to the construction of a groin, breakwater, dam, or beach fill.

1. Gradual buildup of land on a shore due to wave action, tides, currents, airborne material, or alluvial deposits.

2. The process whereby stones or other inorganic masses add to their bulk by adding particles to their surfaces. Also known as aggradation.

3. See <<accretion tectonics>>

The growth of a precipitation particle by the collision of a frozen particle (ice crystal or snowflake) with a supercooled liquid droplet which freezes upon contact.