tridenarius

tridenarius [cf. trideni, CL tricenarius], consisting of thirty, (also w. numerus or as sb.) thirty, group or set of thirty. b (w. officium or as sb. n.) trental, series of thirty (esp. daily requiem) masses (cf. trentalis, tricenalis, tricenarius, tridenalis, trigintalis). in nulla domo eorum [canonicorum] numerus tridenarius excedatur Inst. Sempr. *xlii.  b adhuc de morte tritennarium [Ciren. II 297: de more tricenarium] pro rege celebrabatur officium Ailr. Ed. Conf. 777A.