mĕsŏnyctĭus — Lewis & Short
mĕsŏnyctĭus, a, um, adj., mesonu/ktios,
I of midnight:
afflatus,Isid. 5, 30, 4.— Hence, subst.: † mĕsŏnyctĭum, ii, n., = mesonu/ktion, midnight (post-class.): CVIVS MESONYCTIVM FACTVM EST V. ID. DEC., i. e. midnight apparition, Inscr. Mur. 333.