なんだ Also written なのだ Meanings Auxiliary it is assuredly that ...; can say with confidence that ... See also: のだ. did not ... (after the -nai stem of a verb) Example sentences あらまあ、ホント、全く知らなんだ。Oh my, you're right, I didn't know that at all. Words containing なんだ なんだか (a) little なんだって what?! なんだっけ what is it? And 1 more. Jinuma: Japanese Dictionary · Word lists