Learn how to say Nonplussed correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word nonplussed:
1so surprised and confused that one is unsure how to react:
Henry looked completely nonplussed
2North American informal not disconcerted; unperturbed.
In standard use nonplussed means ‘surprised and confused’, as in
she was nonplussed at his eagerness to help out
. In North American English a new use has developed in recent years, meaning ‘unperturbed’—more or less the opposite of its traditional meaning—as in
he was clearly trying to appear nonplussed
. This new use probably arose on the assumption that non- was the normal negative prefix and must therefore have a negative meaning. It is not considered part of standard English.