Definition
The need to urinate or defecate; a polite way of referring to the need to use the toilet.
便意（委婉说法）
Halfway through the meeting, he had to excuse himself, saying he needed to answer the 'call of nature'.
会议进行到一半，他不得不借口离开，说他需要回应『大自然的召唤』。
After the long hike, I finally couldn't ignore the 'call of nature'.
在长途远足后，我终于无法忽视『大自然的召唤』。
She felt the 'call of nature' and quickly looked for a restroom.
她感觉到『大自然的召唤』，迅速寻找洗手间。