Definition of tuff in US English:



  • A light, porous rock formed by consolidation of volcanic ash.

    • ‘Increasing proximity to a subduction zone during plate convergence is indicated by the appearance of felsic tuff.’
    • ‘It also follows that there are differences in age between grains, which is consistent with the impression of resorption given by the grain morphology: possibly all grains predate the final tuff volcanism.’
    • ‘The lower series consists of alternating basalt lava, tuff breccia, tufite, and siliceous rock, whereas the upper one is dominated by diabase.’
    • ‘Among the 30 different types of stone recognized are varieties of diorite, granite, bedded tuff, sandstones, limestones, and tufa.’
    • ‘Lenses incorporate varicoloured tuffaceous cherts intercalated with tuffaccous mudstone and tuff.’


Mid 16th century: via French from Italian tufo, from late Latin tofus, Latin tophus (see tophus).