頓口無言 [顿－无－]

Jyutping deon6 hau2 mou4 jin4
Pinyin dùn kǒu wú yán

Definitions (Wiktionary)
  1. phrase, idiomatic
    to have nothing to say in response
Definitions (Kaifangcidian)
  1. （沒有對應漢語詞彙）