tataranieto

great-great-grandchild; great-great-grandson (great-great-granddaughter for the feminine form)

From tras- + Old Spanish trasnieto (“great-grandchild”), from tras- + nieto (“grandson”), formed from nieta (“granddaughter”), from Late Latin nepta, from Latin neptis, from Proto-Indo-European *néptih₂. Compare Latin nepōs (“grandson, grandaughter, nephew, niece”) (genitive singular nepōtis).