質問: These verbs: * いらっしゃる * おっしゃる * くださる * なさる * More? Are all listed as 五段 verbs, but they don't follow the usual conjugation rules for them. For example: * 命令形: いらっしゃる -> いらっしゃい, not いらっしゃれ * 連用形: Same as above, not いらっしゃり Is there a separate name/classification for these types of verbs? Such as カ変 for 来る and サ変 for する.
回答: dainichi's comment in the OP is right. These are left-overs of western dialect that are actually still used today: **Wants** たい ー> とう (usually in the negative) * 行きたくないな・行きとうないな or 行きとうなかね **て/た forms of 「う」verbs** * 何買ったの?・なんこうたと? **General Phonetic Shift** ら行 sounds to い * それ何?・そいなん? * その人誰?・そん人だいね? * 二人は?・ふたいは? **Scolding** * 早く行きなさいよ!・はよう行きんしゃい! With these it's easy to see how ありがとう and いらっしゃい came about.