Under the weather: Feeling sick; not well. When a sailor gets sick on a boat, they would go under the deck and away from the weather to get better. This phrase became popular to express sickness.
As in I really feel under the weather today.
中文释义：under the weathe的意思是:身体不舒服，心情不好。以前水手出海远航的时候，在烈日曝晒之下，部分水手晕船加中暑，他们就会躲到甲板，这样就远离糟糕的天气，因此用under the weather来指代心情不好，或感觉不舒服。这个短语通常也写成feel under the weather。
例句：I really feel under the weather today. I think I havea cold.（我今天不是很舒服，我应该是感冒了。）