不成文 [－－－]

Jyutping bat1 sing4 man4
Pinyin bù chéng wén

Definitions (CC-CEDICT)
  1. unwritten (rule)
Definitions (粵典–words.hk)
  1. x
Definitions (Wiktionary)
  1. adj, attributive
    unwritten; conventional; customary; implied
Definitions (Kaifangcidian)
  1. （沒有對應漢語詞彙）