無無端端 [无无－－]

Jyutping mou4 mou4 dyun1 dyun1
Pinyin wú wú duān duān

Definitions (CC-CANTO)
  1. (adverb) unreasonably; suddenly; unexpectedly
Definitions (粵典–words.hk)
  1. x
Definitions (Kaifangcidian)
  1. 無緣無故 – 无缘无故