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Related to tuff: tough
A rock composed of compacted volcanic ash varying in size from fine sand to coarse gravel.
[French tuf, from Old French, from Old Italian tufo, tufa; see tufa.]
tuff·a′ceous (tŭ-fā′shəs) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Geological Science) a rock formed by the fusing together on the ground of small rock fragments (less than 2 mm across) ejected from a volcano
[C16: from Old French tuf, from Italian tufo; see tufa]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
a fragmental rock consisting of the smaller kinds of volcanic detritus, as ash or cinder, usu. more or less stratified.
[1560–70; < Middle French tuf(e) < Italian tufo. See tufa]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
A rock made up of particles of volcanic ash, varying in size from fine sand to coarse gravel.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A rock made up of compacted volcanic ash; also known as tufa.
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited