Word Study
Lapilli (root: lapillus)
CIDE DICTIONARY
Lapilli, n. pl. [L. lapillus a little stone, dim. of lapis stone.].
Volcanic ashes, consisting of small, angular, stony fragments or particles. [1913 Webster]
OXFORD DICTIONARY
Lapilli, n.pl. stone fragments ejected from volcanoes.
Etymology
It. f. L, pl. dimin. of lapis stone
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