accretion

noun10

1. •
   (Gradual) increase by an external addition of matter; (countable) an instance of this.

   • A mineral augments not by growth, but by accretion.
2. •
   The process by which material is added to a geological feature; specifically, to a tectonic plate at a subduction zone.
3. •
   Followed by of: external addition of matter to a thing which causes it to grow, especially in amount or size.

   • [W]hile some fevv grevv rich by turning Money in their ovvn Banks, there vvas a false Appearance of VVealth vvithin, but no Accretion of Riches from abroad. — 1713
4. •
   Something gradually added to or growing on a thing externally.
5. •
   A substance which has built up on the surface of an object, rather than become embedded in it.

   • Accretions of dirt on clothing are often left in place by conservators because they can provide additional details about the artefact’s importance or history.
6. •
   The process of separate particles aggregating or coalescing together; concretion; (countable) a thing formed in this manner.

   • The accretion of particles forms a solid mass.
7. •
   The formation of planets, stars, and other celestial bodies by the aggregating of matter drawn together by gravity; also, the growth of a celestial body through this process.
8. •
   Increase by natural growth, especially the gradual increase of organic bodies by the internal addition of matter; organic growth; also, the amount of such growth.

   • Warwick was unable to perceive much change in the market-house. […] There might have been a slight accretion of the moss and lichen on the shingled roof. — 1900
9. •
   Increase in property by the addition of other property to it (for example, gain of land by alluvion (“the deposition of sediment by a river or sea”) or dereliction (“recession of water from the usual watermark”), or entitlement to the products of the property such as interest on money); or by the property owner acquiring another person’s ownership rights; accession; (countable) an instance of this.
10. •
    Increase of an inheritance to an heir or legatee due to the share of a co-heir or co-legatee being added to it, because the latter person is legally unable to inherit the share.