Listen to 上二段活用 上二段活用 かみにだんかつよう conjugation (inflection, declension) of nidan verbs (resulting in a stem of either "i" or "u" for every conjugation)
Listen to 下二段活用 下二段活用 しもにだんかつよう conjugation (inflection, declension) of nidan verbs (resulting in a stem of either "e" or "u" for every conjugation)
Listen to 上一段活用 上一段活用 かみいちだんかつよう conjugation (inflection, declension) of ichidan verbs ending in "iru"
Listen to 下一段活用 下一段活用 しもいちだんかつよう conjugation (inflection, declension) of ichidan verbs ending in "eru"