also: なーんだ · なあんだ
what!; oh!
Expresses surprise, realization, or mild disappointment. Often drawn out as なーんだ or なあんだ.
なんだ、もう終わったのか。
Oh, it's already over?
what the heck; what the; damn
Only with reading なんだ
Stronger exclamation of annoyance, disbelief, or frustration. Restricted to the reading なんだ.
なんだ、このやろう！
What the hell, you jerk!
Oh, is that all it was?
What the heck, calling me out so suddenly.
ちぇっ is a short click of annoyance or disgust, while なんだ in its sharper use expresses indignant disbelief, often before a complaint.
あら is a softer, often feminine exclamation of mild surprise, whereas なんだ can be used by anyone and often carries a note of anticlimax.
へえ shows interested surprise at new information, while なんだ (なーんだ) shows surprise that resolves into disappointment or relief.
なに is the neutral question word for 'what', while 何だ(なんだ) is an interjection used alone to show surprise or annoyance rather than to ask a question.
Kanji spelling; may be encountered but kana is preferred.
Drawn-out casual variant expressing realization or mild disappointment.
Alternative drawn-out spelling, similar to なーんだ.
Contraction of 何 (なに, 'what') + だ (copula). The interjection use developed from rhetorical questions.