forthwith
/ˈfɔːθˈwɪθ/adverb
- (especially in official use) immediately; without delay〈官〉立即; 毫不延迟地：
we undertake to pay forthwith the money required
我们同意立即支付所需资金。
词源
Middle English （in the sense 'along with, at the same time'）： partly from earlier forthwithal, partly representing forth with used alone without a following noun.