老人精 [－－－]

Jyutping lou5 jan4 zing1
Pinyin lǎo rén jīng

Definitions (CC-CANTO)
  1. describes a child who acts like an adult; a young but worldly person
Definitions (粵典–words.hk)
  1. 名詞
    失去​童真​、​過於​世故​嘅​細​路
    child who acts and talks like an adult, e.g. one that focuses on money or routine work; literally: old man spirit
  2. 近義詞
    老積