大晦日[oomisoka] New Year's Eve
韜晦[toukai] hidden (talents, etc.)
晦渋[kaijuu] ambiguous
晦冥[kaimei] darkness
大晦[ootsugomori] the last day of the year

晦ます[kuramasu] to abscond
晦む[kuramu] to be dazzled by
自己韜晦[jikotoukai] concealing one's talents, position, status, intentions, etc.
天地晦冥[tenchikaimei] The world is covered in darkness

正朔[seisaku] beginning of the month or the year
八朔[hassaku] Hassaku orange (Citrus hassaku)
朔風[sakufuu] north wind
朔望[sakubou] first and fifteenth days of the lunar month (corresponding to new moon and full moon)

朔望月[sakubougetsu] synodic month
朔望潮[sakubouchou] spring tide
告朔[kousaku] ceremony where the Emperor would inspect the records of attendance and absence of officials