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

いとも簡単に[itomokantanni] very easily
英単語[eitango] English word
欧州通貨単位[oushuutsuukatani] European Currency Unit
簡単[kantan] simple
簡単に言うと[kantanniiuto] simply put

簡単に言えば[kantanniieba] simply put
口辺単純疱疹[kouhentanjunhoushin] cold sore
構成単位[kouseitani] element
十二単[juunihitoe] twelve-layered ceremonial kimono (worn by a court lady)
全単射[zentansha] bijection