Wu Collection, Middle Volume Radical: Sickness (bù) Pains: 17 Page 780, Entry 06 Tang Rhymes (Tangyun) and Collected Rhymes (Jiyun) state it is pronounced lao (falling tone). Explanation of Characters (Shuowen): In Joseon, medicinal poison is called lao. Extended Rhymes (Guangyun): Lao refers to a malicious person. Yangzi's Regional Expressions (Fangyan): Regarding any drinking of medicine or application of medicine that causes poisoning, it is called lao between Northern Yan and Joseon. Commentary: Lao and li both refer to a pungent, stinging sensation. Also, according to Fine Gleanings (Boya), it means pain. Also, according to Collected Rhymes (Jiyun), it is pronounced liao. Also, it is pronounced lao. The meaning is the same. Also, according to Correct Character Mastery (Zhengzitong), people today use the term lao for a condition of accumulated exhaustion resulting in illness.