Meaning of ATTO- in English

ATTO-

combining form Etymology: International Scientific Vocabulary, from Danish or Norwegian atten eighteen, from Old Norse āttjān; akin to Old English eahtatīene eighteen one quintillionth (10 -18 ) part of

Merriam Webster. Explanatory English dictionary Merriam Webster.      Толковый словарь английского языка Мерриам-Уэбстер.