一元[ichigen] unitary
一元化[ichigenka] unification
一元的[ichigenteki] monistic
一元論[ichigenron] monism
一次元[ichijigen] one dimensional

一新紀元[isshinkigen] new era
隠元[ingen] beans
隠元豆[ingenmame] common bean (Phaseolus vulgaris)
家元[iemoto] head of a school (of music, dance)
火の元[hinomoto] origin of fire

哀歌[aika] lament (song)
愛唱歌[aishouka] (one's) favourite song
詠歌[eika] poem (esp. tanka)
艶歌[enka] enka
応援歌[ouenka] rooters' song

歌い合う[utaiau] to sing responsively
歌い上げる[utaiageru] to sing at the top of one's voice
歌詠み[utayomi] tanka composer
歌会[utakai] poetry party or competition