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

１月[ichigatsu] January
ひと月[ichigetsu] one month
下弦の月[kagennotsuki] waning moon
何ヶ月[nankagetsu] how many months?
何月[nangatsu] what month

佳月[kagetsu] good month
か月[kagetsu] (number of) months
花鳥風月[kachoufuugetsu] beauties of nature
各月[kakugetsu] every month
隔月[kakugetsu] every second month

隠しカメラ[kakushikamera] hidden camera
隠し引き出し[kakushihikidashi] secret withdrawal
隠し芸[kakushigei] hidden talent
隠し撮り[kakushidori] taking pictures secretly
隠し子[kakushigo] illegitimate child

隠し事[kakushigoto] secret
隠し場所[kakushibasho] cache
隠し食い[kakushigui] eating on the sly
隠し立て[kakushidate] secrecy
隠くす[kakusu] to hide