accretion

American  

[uh-kree-shuhn] / əˈkri ʃən /

noun

1. an increase by natural growth or by gradual external addition; growth in size or extent.

2. the result of this process.

3. an added part; addition.

   The last part of the legend is a later accretion.

4. the growing together of separate parts into a single whole.

5. Law. increase of property by gradual natural additions, as of land by alluvion.

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accretion British  

/ əˈkriːʃən /

noun

1. any gradual increase in size, as through growth or external addition

2. something added, esp extraneously, to cause growth or an increase in size

3. the growing together of normally separate plant or animal parts

4. pathol

   1. abnormal union or growing together of parts; adhesion

   2. a mass of foreign matter collected in a cavity

5. law an increase in the share of a beneficiary in an estate, as when a co-beneficiary fails to take his share

6. astronomy the process in which matter under the influence of gravity is attracted to and increases the mass of a celestial body. The matter usually forms an accretion disc around the accreting object

7. geology the process in which a continent is enlarged by the tectonic movement and deformation of the earth's crust

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accretion Scientific  

/ ə-krē′shən /

1. Geology The gradual extension of land by natural forces, as in the addition of sand to a beach by ocean currents, or the extension of a floodplain through the deposition of sediments by repeated flooding.

2. Astronomy The accumulation of additional mass in a celestial object by the drawing together of interstellar gas and surrounding objects by gravity.

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Other Word Forms

• nonaccretion
  noun
• accretionary
  adjective
• accretive
  adjective

Etymology

Origin of accretion

First recorded in 1605–15; from Latin accrētiōn- (stem of accrētiō ), equivalent to accrēt(us), past participle of accrēscere “to grow” ( ac- prefix meaning “toward” + crē- “grow” + -tus past participle suffix) + -iōn- noun suffix; see ac-, -ion

Explanation

The process of increasing can be called accretion. Although you may say that stalactites "grow" from the ceilings of caves, they actually form from an accretion of limestone and other minerals. So what's the difference between an addition and an accretion? Addition implies adding to something that already exists, such as an addition to the cast (when a new actor joins an existing show). The noun accretion, on the other hand, implies an accumulation that causes increase, such as "an accretion of frost on the windows" or "an accretion of plaque on your teeth." The latter, of course, is why the dentist always begs you to floss and brush.

Example Sentences

See Examples For:

accretion

The observations confirmed that a young star's accretion rate, or the speed at which it gathers material, naturally slows as it ages.

From Science Daily ● Jul. 5, 2026

As gas and dust spiral inward, they form an accretion disk that emits enormous amounts of energy, including powerful X-rays.

From Science Daily ● Jun. 19, 2026

BOQ expects ROE accretion of 15-25 basis points.

From The Wall Street Journal ● Apr. 8, 2026

Phased capacity addition ensures margin accretion via utilization and higher integration.

From The Wall Street Journal ● Mar. 24, 2026

Most of them are in the ancient lunar highlands and date from the time of the final accretion of the Moon from interplanetary debris.

From "Cosmos" by Carl Sagan

Related Words

• accumulation