無師自通 [无师－－]

Jyutping mou4 si1 zi6 tung1
Pinyin wú shī zì tōng

Definitions (CC-CEDICT)
  1. self-taught
  2. to learn without a teacher (idiom)
Definitions (粵典–words.hk)
  1. 語句
    冇​其他人​教​，​靠​自己​學識​一種​技術
    to master a skill without a teacher; to be self-taught
Definitions (Wiktionary)
  1. phrase, idiomatic
    to be self-taught; to have learnt something without having been taught by a teacher
Definitions (Kaifangcidian)
  1. （沒有對應漢語詞彙）