This is not actually a word, but is a non-verbal statement often misunderstood by men. A "loud sigh" means she thinks you are an idiot at that moment, and wonders why she is wasting her time standing here arguing with you over "Nothing".
这不是一句话，而是非言辞的一种表达，它常被男人误解。女人大声叹息意味着她认为那一刻的你实在是一个白痴，而且不明白自己为什么浪费了这么多时间站在这里来跟你争论一些“没什么”的事情.