The term 'non-plussed' represents a state of perplexity or confusion. However, there are many other words that have similar meanings such as dumbfounded, bewildered, stumped, flummoxed, confounded, mystified, and puzzled, among others. Each of these words can be used in a different context to indicate someone who is completely taken aback or baffled by a particular situation or event. Depending on the tone and context, each of these synonyms can be interchanged with 'non-plussed' to convey a similar meaning. It is essential to choose the right word based on the intensity of the situation and the desired effect on the reader.