Black's Law Dictionary (2nd edition)dictionaries

Forthwith

As soon as, by reason-able exertion, confined to the object, a thing may be done. Thus, when a defendant is ordered to plead forthwith, he must plead within twenty-four hours, when a statute enacts that an act is to be doue “forthwith,” it means that the act is to be done within a reasonable time. 1 Chit. Archb. Pr. (12th Ed.) 164; Dickerman v. Northern Trust Co., 176 U. S. 181, 20 Sup. Ct. 311, 44 L. Ed. 423.; Faivre v. Manderscheld, 117 Iowa, 724, 90 N. W. 76; Martin v. Pifer, 96 Ind. 248

Source: Black's Law Dictionary 2nd Ed (1910)