a fragmental rock consisting of the smaller kinds of volcanic detritus, as ash or cinder, usually more or less stratified.
Origin of tuff2
1560–70; < French tuf < Italian tufo. See tufa
Also called volcanic tuff.
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Examples from the Web for tuffaceous
Agglomeratic and tuffaceous rocks are of quite common occurrence, although less important than the lavas.Mount Rainier|Various
a rock formed by the fusing together on the ground of small rock fragments (less than 2 mm across) ejected from a volcano
Word Origin for tuff
C16: from Old French tuf, from Italian tufo; see tufa
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
advertiser's spelling of tough (adj.), attested by 1940.
Online Etymology Dictionary, © 2010 Douglas Harper
A rock made up of particles of volcanic ash, varying in size from fine sand to coarse gravel.
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