zettabyte /ˈzɛtəbaɪt/ noun2 •One sextillion (10²¹, or 1,000,000,000,000,000,000,000) bytes or 1,000 exabytes.Conservative estimates put data produced in 2020 alone at 44 zettabytes. — 2015 •(informal) A zebibyte. formszettabytes