ὑπ-όμνῡμι · hyp-omnymi — LSJ
interpose by oath
interpose by oath, φῂς ὑπομνύς S. Fr. 339 codd. (ἐπομνύς Pearson).
II make oath, apply for a postponement of the trial, applied for an extension of the term, affidavit being put in by way of excuse
Med., in Att. law, make oath (for oneself or another) that something serious prevents a personʼs appearing in court at the due time, and so apply for a postponement of the trial, D. 47.39, etc.; ὑ. τινὰ δημοσίᾳ ἀπεῖναι στρατευόμενον Id. 48.25; τὸν Δημοσθένην τις ὑπωμόσατο ὡς νοσοῦντα applied for an extension of the term for Demosthenes on the plea of sickness, Id. 58.43: hence, comically, ὑπώμνυτο ὁ μὲν οἶνος ὄξος αὑτὸν εἶναι γνήσιον, τὸ δʼ ὄξος οἶνον αὑτὸ μᾶλλον θατέρου Eub. 65:—Pass., ὑπομοθέν
2 make an objection on oath
in the Assembly or Boule, make an objection on oath, X. HG 1.7.34, Plu. VOrat. 2.848d, Poll. 8.44.