speechless

speechless
speech‧less /ˈspiːtʃləs/ adjectiveunable to speak because you feel very angry, upset etc
    speechless with
    His comments left me speechless with rage.
—speechlessly adverb
—speechlessness noun [uncountable]
     

THESAURUS

   ▪ surprised having the feeling you get when something happens that you did not expect: I was surprised to see her again so soon. | I’m really surprised that he remembered my birthday. | Nobody was surprised when they split up. | a surprised expression
   ▪ amazed [not before noun] extremely surprised, especially by something good or by something that seems hard to believe: I’m amazed that he survived. | You’ll be amazed when you see the difference.
   ▪ astonished extremely surprised: He was astonished by how much she had changed. | an astonished look
   ▪ astounded extremely surprised or shocked. Astounded sounds a little more formal and a little stronger than astonished: She was astounded by how much it cost.
   ▪ staggered/flabbergasted/dumbfounded [not before noun] extremely surprised or shocked: ‘What?’ I said, utterly staggered by his answer. | She just sat there looking flabbergasted.
   ▪ stunned so surprised that you do not know what to do or say: I was too stunned to protest. | Everyone seemed stunned by his outburst. | They listened in stunned silence.
   ▪ speechless so surprised that you cannot speak: I was speechless when I heard that I’d won.
   ▪ taken aback [not before noun] surprised by what someone says or does, so that you are not sure how to react: I was a little taken aback by her question. | Sharpe was somewhat taken aback by the girl 's directness.
   ▪ nonplussed /nɒnˈplʌst $ nɑːn-/ formal surprised and a little confused: She was nonplussed by such an odd question.
   ▪ gobsmacked [not before noun] British English informal extremely surprised – a very informal use: I was absolutely gobsmacked when they told me I had passed.