noun

• The act of increasing by natural growth; especially the increase of organic bodies by the internal accession of parts; organic growth.
• The act of increasing, or the matter added, by an accession of parts externally; an extraneous addition.
• Something added externally to promote the external growth of an item.
• Concretion; coherence of separate particles.
• (biology) A growing together of parts naturally separate, as of the fingers or toes.
• (geology) The gradual increase of land by deposition of water-borne sediment.
• (law) The adhering of property to something else, by which the owner of one thing becomes possessed of a right to another; generally, gain of land by the washing up of sand or soil from the sea or a river, or by a gradual recession of the water from the usual watermark.
• (law) Gain to an heir or legatee; failure of a coheir to the same succession, or a co-legatee of the same thing, to take his share percentage.
• (astrophysics) The formation of planets and other bodies by collection of material through gravity.
• (conservation) Built-up matter lying on top of, rather than embedded in, a surface.