IPA: /ˈdʌmstrʌk/
KK: /dʌmstrʌk/
Feeling so surprised or shocked that you cannot speak or react.
She was dumbstruck when she heard the unexpected news.
Dumbstruck → It is formed from "dumb" (from Old English "dumb", meaning unable to speak) and "struck" (from Old English "strucan", meaning to strike or hit). The word "dumbstruck" describes a state of being so shocked or surprised that one is unable to speak, as if struck by a sudden blow.
Think of being so shocked that you are 'unable to speak' ('dumb') because something has 'struck' you unexpectedly.