adverb

(especially in official use) immediately; without delay.

we undertake to pay forthwith the money required

immediately,at once,instantly,directly,right away,straight away,now,this/that (very) minute,this/that instant,then and there,there and then,here and now,in/like a flash,instantaneously,by return,post-haste,without delay,without further/more ado,without hesitation,unhesitatingly,quickly,as quickly as possible,fast,speedily,with all speed,promptly,as soon as possible,ASAP,expeditiously,momentarily,in short order,tout de suite,straight off,toot sweet,pronto,double quick,p.d.q. (pretty damn quick),in double quick time,at warp speed,ekdam,straightway,instanter,forthright