いい年をして[iitoshiwoshite] (in spite of) being old enough to know better
亥年[idoshi] year of the boar
一箇年[ikkanen] one year
一周年[isshuunen] one full year
一年以内に[ichineninaini] within a year

一年間[ichinenkan] (period of) one year
一年生[ichinensei] annual (plant)
一年草[ichinensou] annual (plant)
一年ぢゅう[ichinenjuu] all year round
一両年[ichiryounen] (a) year or two

悔改める[kuiaratameru] to repent
改まる[aratamaru] to be renewed
改めて[aratamete] another time
改める[aratameru] to change
改悪[kaiaku] deterioration

改印[kaiin] changing seals
改革[kaikaku] reform
改革案[kaikakuan] reform proposal
改革過程[kaikakukatei] reform process
改憲[kaiken] constitutional change