forthwith[adverb]Synonyms: at once, directly, immediately, instantly, quickly, right away, straightaway, without delay
[TahlilGaran] English Synonym Dictionary ▲
forth‧with /fɔːθˈwɪð, -ˈwɪθ $ fɔːrθ-/
adverb formal immediately:
He was fined £40, with 28 days’ imprisonment if the money was not produced forthwith. [TahlilGaran] Dictionary of Contemporary English ▲