a. Growth or increase in size by gradual external addition, fusion, or inclusion.
b. Something contributing to such growth or increase: "the accretions of paint that had buried the door's details like snow" (Christopher Andreae).
2. Biology The growing together or adherence of parts that are normally separate.
a. Slow addition to land by deposition of water-borne sediment.
b. An increase of land along the shores of a body of water, as by alluvial deposit.
4. Astronomy An increase in the mass of a celestial object by its gravitational capture of surrounding interstellar material.
[Latin accrētiō, accrētiōn-, from accrētus, past participle of accrēscere, to grow; see ACCRUE.]
ac·cretion·ar′y (-shə-nĕr′ē), ac·cretive adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.