octavo
/ɒkˈteɪvəʊ/(缩略词：8vo)
noun
(pl. -os)
1- a size of book page that results from folding each printed sheet into eight leaves (sixteen pages)八开本; 八开。
1.1
- a book of this size八开本的书。
词源
late 16th cent.: from Latin in octavo 'in an eighth', from octavus 'eighth'.