An interjection expressing surprise, disbelief, or annoyance (like “Eh!?”, “What!?” or “Come on!”). Used as a spontaneous reaction in conversation.
ええっ、本当に来るの？
Eh!? You're really coming?
ええっ、そんなこと知らなかったよ。
What!? I didn't know that.
ええっ！財布を忘れたの？信じられない。
What!? You forgot your wallet? I can't believe it.