forthwith
adv. US //ˈfɔɹθˈwɪθ// UK //fˈɔːθwɪθ// forth·with
From Middle English forth-with (“at once, immediately; at the same time, already; straight ahead”) [and other forms], partly from the phrase forth with (something), and partly from forth-with-al, furth-with-al (“at once, immediately; together with”) (whence forthwithal).