An interjection in Tohoku dialect used as an affirmative response—like 'that's right' or 'uh-huh.'
A: 明日は来られるべか？ B: んだ、行ぐよ。
A: Can you come tomorrow? B: Yeah, I'll go.
話を聞いて、みんなが『んだ』と頷いた。
Hearing the story, everyone nodded and said, 'mm-hmm.'
年配の人は会話で『んだ』をよく使う。
Older people often use 'nda' in conversation.