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

それ以来[soreirai] since then
出来るようになる[dekiruyouninaru] (something) has become possible
やって来る[yattekuru] to come along
ぴんと来る[pintokuru] to get (a joke or explanation)
以来[irai] since

遠来[enrai] foreign or distant visitor
往来[ourai] coming and going
家来[kerai] retainer
外来[gairai] external origin
外来患者[gairaikanja] outpatients