墊腳石 [垫脚－]

Jyutping din3 goek3 sek6
Pinyin diàn jiǎo shí

Definitions (CC-CEDICT)
  1. stepping stone
  2. fig. person used to advance one's career
Definitions (Wiktionary)
  1. noun, figuratively
    stepping stone; person or thing used to advance one's career
  2. noun
    stepping stone (stone used to cross or mount something)