proviso
/prəʊˈvaɪzəʊ/noun
(pl. -os)
- a condition attached to an agreement附带条件, 附文; 但书：
he let his house with the proviso that his own staff should remain to run it.
他出租宅邸的一个附加条件是原有工作人员必须保留下来进行管理。
词源
late Middle English: from the medieval Latin phrase proviso （quod） 'it being provided (that)'，from Latin providere 'foresee，provide'.