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definitions

clast

[klast]
noun
  1. a grain of sediment, silt, sand, gravel, etc., especially as a constituent fragment of a clastic rock formation, as distinguished from a chemical or biogenic component of such a formation.

Origin of clast

First recorded in 1950–55; probably back formation from clastic
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
clast in Science

clast

[klăst]
  1. A rock fragment or grain resulting from the breakdown of larger rocks.
Related formsclastic adjective (klăs′tĭk)
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.