Definition of lapilli in English:


plural noun

  • Rock fragments ejected from a volcano.

    • ‘We thought they might be lapilli - little volcanic hailstones that form when you have an eruption of volcanic ash and it coagulates and falls out.’
    • ‘Atmospheric aggregates include: fine particles lodged in the vesicles of larger grains; ash clots and flakes bound by electrostatic forces; accretionary lapilli, pellets or mud-drops formed by wet particle adhesion.’
    • ‘We infer that the framework through which transport took place consists of lapilli lodged within elutriation networks similar to those observed in the field (vertical ‘pipes’ having elongated sheet-like forms in three dimensions).’
    • ‘Some matrix ash samples were also analysed to ensure that the complete geochemical range could be assessed, and where lapilli were not available.’
    • ‘Mount Vesuvius' eruption buried the ancient Roman city of Pompeii in volcanic ash and lapilli, preserving it in its current ghost-town-like state.’


Mid 18th century (in the general sense ‘stones, pebbles’): via Italian from Latin, plural of lapillus, diminutive of lapis ‘stone’.