ac·​cre·​tion | \ ə-ˈkrē-shən How to pronounce accretion (audio) \

Definition of accretion

1 : the process of growth or enlargement by a gradual buildup: such as
a : increase by external addition or accumulation (as by adhesion of external parts or particles)
b : the increase of land by the action of natural forces
2 : a product of accretion especially : an extraneous addition accretions of grime

Keep scrolling for more

Other Words from accretion

accretionary \ ə-​ˈkrē-​shə-​ˌner-​ē How to pronounce accretionary (audio) , -​ˌne-​rē \ adjective

Did You Know?

The slow accretion of scientific knowledge over many centuries has turned into an avalanche in our time. Any accretion of ice on a grounded jet will result in takeoff delays because of the danger it poses. The land area of the Mississippi Delta increases every year from the accretion of soil washed down the Mississippi River, though the accretions happen so slowly that it's difficult to detect any increase at all. Accretion is often used in scientific writing; its usual verb form, accrue, is more often used in financial contexts ("This figure doesn't count the accrued interest on the investments").

Examples of accretion in a Sentence

rocks formed by the slow accretion of limestone There was an accretion of ice on the car's windshield.
Recent Examples on the Web This is a novel that works not through dazzling images or narrative pyrotechnics but through the steady accretion of clear-eyed observations relayed in limpid prose. Heller Mcalpin, The Christian Science Monitor, "‘Monogamy’ reveals conflicted emotions over a long marriage," 17 Sep. 2020 The next goal is to obtain a sequence of images or a video, showing the time variability of the accretion flow around the black hole. Avi Loeb, Scientific American, "A Movie of the Evolving Universe, Potentially Scary," 2 Aug. 2020 The impunity of the American police has been achieved by slow accretion through the decades, and with the tacit understanding that it would be deployed in great disproportion against black people. Jelani Cobb, The New Yorker, "An American Spring of Reckoning," 14 June 2020 Although black holes themselves are invisible, the disk of material around them, called accretion disks, produce X-ray light that sensitive telescopes and satellites like XMM-Newton can detect. Ashley Strickland, CNN, "Astronomers witness the steadfast beating heart of a black hole," 12 June 2020 Unlike the high-speed collisions between planetesimals in hierarchical accretion, in particle-cloud collapse, particles merge gently, slowly growing larger. Fox News, "NASA’s New Horizons mission sheds new light on how planets form," 15 Feb. 2020 The other prevailing theory was called hierarchical accretion, where objects from different areas of the solar nebula would collide to form an object. Ashley Strickland, CNN, "Distant object in our solar system could show how planets form, scientists reveal," 13 Feb. 2020 There has been a steady accretion of power by the executive, often as a result of a supine legislative branch. Dan Balz, Anchorage Daily News, "Analysis: Pelosi’s impeachment decision sets up an epic constitutional battle - and a personal one," 26 Sep. 2019 The accretion of ills surely skirts the edge of overwhelming., "Can you name five women artists? It’s not me who’s asking. It’s the Museum of Fine Arts, right there on the wall at the entry to “Women Take the Floor,” the museum’s kickoff exhibition of what’s shaping up to be a sesquicentennial year of self-recriminating atonement.," 20 Sep. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'accretion.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of accretion

1615, in the meaning defined at sense 1

History and Etymology for accretion

borrowed from Latin accrētiōn-, accrētiō "increase," from accrē- (stem of accrēscere "to increase, be added") + -tiōn-, -tiō, suffix of action nouns — more at accrue

Keep scrolling for more

Learn More about accretion

Time Traveler for accretion

Time Traveler

The first known use of accretion was in 1615

See more words from the same year

Statistics for accretion

Last Updated

27 Sep 2020

Cite this Entry

“Accretion.” Dictionary, Merriam-Webster, Accessed 19 Oct. 2020.

Keep scrolling for more

More Definitions for accretion


How to pronounce accretion (audio)

English Language Learners Definition of accretion

: a gradual process in which layers of a material are formed as small amounts are added over time
: something that has grown or accumulated slowly : a product or result of gradual growth


ac·​cre·​tion | \ ə-ˈkrē-shən How to pronounce accretion (audio) \

Medical Definition of accretion

: the process of growth or enlargement especially : increase by external addition or accumulation (as by adhesion of external parts or particles) — compare apposition sense 1, intussusception sense 2

Other Words from accretion

accretionary \ -​shə-​ˌner-​ē How to pronounce accretionary (audio) \ adjective


ac·​cre·​tion | \ ə-ˈkrē-shən How to pronounce accretion (audio) \

Legal Definition of accretion

1 : the process or a result of growth or enlargement: as
a : the increase or extension of the boundaries of land or the consequent acquisition of land accruing to the owner by the gradual or imperceptible action of natural forces (as 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) also : accession in which the boundaries of land are enlarged by this process — compare avulsion, reliction
b : increase in the amount or extent of any kind of property or in the value of any property accretions to a trust fund resulting from the increase in value of…securities in which its corpus is investedIn re Estate of Gartenlaub, 244 P. 348 (1926)

Note: Accretion in value of the principal of a trust is generally not considered income.

c : enlargement of a bargaining unit by the addition of new employees
2 in the civil law of Louisiana : the passing to an heir or conjoint legatee of the right to accept a portion of a succession resulting from the failure of a coheir or colegatee to take his or her own share

Keep scrolling for more

Comments on accretion

What made you want to look up accretion? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

Farm Idioms Quiz

  • cow coming home
  • What does 'poke' refer to in the expression 'pig in a poke'?
Spell It

Can you spell these 10 commonly misspelled words?

Add Diction

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!