異姓[isei] different surname
下姓[geshou] person of humble birth
改姓[kaisei] changing one's family name
旧姓[kyuusei] one's former (maiden) name
姓氏[seishi] full name

姓名[seimei] full name
種姓[sujou] birth
俗姓[zokushou] secular surname (of a priest)
他姓[tasei] another surname

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