verso
/ˈvɜːsəʊ/noun
(pl. -os)
1
- a left-hand page of an open book, or the back of a loose document（一本打开的书的）左页; （散页文件的）背面。与 RECTO相对。
2
- the reverse of something such as a coin or painting（硬币、绘画等的）反面, 背面。
词源
mid 19th cent.: from Latin verso （folio） 'on the turned (leaf)'.