1. nonplus - Noun
2. nonplus - Verb
A state or condition which daffles reason or confounds judgment; insuperable difficalty; inability to proceed or decide; puzzle; quandary.
To puzzle; to confound; to perplex; to cause to stop by embarrassment.
Source: Webster's dictionaryThis beats me! Source: Internet
Got me--I don't know the answer! Source: Internet
a vexing problem Source: Internet
This question really stuck me Source: Internet