Definition of forthwith adverb from the Oxford Advanced Learner's Dictionary

 

forthwith

 adverb
adverb
BrE BrE//ˌfɔːθˈwɪθ//
 
; NAmE NAmE//ˌfɔːrθˈwɪθ//
 
; BrE BrE//ˌfɔːθˈwɪð//
 
; NAmE NAmE//ˌfɔːrθˈwɪð//
 
(formal)
 
jump to other results
immediately; at once The agreement between us is terminated forthwith. Word Origin 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.
See the Oxford Advanced American Dictionary entry: forthwith