nonplus
definition
to render someone unable to react or respond due to surprise or bewilderment
example
The sudden announcement of a mandatory company reorganization completely nonplussed the employees, leaving them uncertain about their future.
synonyms
perplexbewilderconfound
word origin — The word originates from the Latin 'non plus', meaning 'no more' or 'not more', which in English comes to mean a state of being unable to respond or continue due to astonishment.