勘違いかんちがい Common Noun Irregular Intransitive English jmdict 1 noun (common) (futsuumeishi) noun or participle which takes the aux. verb suru intransitive verb misunderstanding;mistaken idea;wrong guess 彼はクラスで一番頭がいいと勘違いしている。 He has the illusion that he is the smartest in his class.