non·plussed also US non·plused 
/ˌnɑ:nˈplʌst/ adjective
not used before a noun /ˌnɑ:nˈplʌst/ adjective [more nonplussed; most nonplussed] formal : so surprised or confused by something that you do not know what to say, think, or do : perplexed
▪ He was nonplussed by his daughter's confession that she had stolen the CD. ▪ She looked slightly nonplussed at first but composed herself quickly.
▪ He was nonplussed by his daughter's confession that she had stolen the CD. ▪ She looked slightly nonplussed at first but composed herself quickly.
