What is to puzzle; to confound; to perplex; to cause to stop by embarrassment. He has been nonplused by Mr. Dry's desiring him to tell what it was that he endeavored to prove. Spectator called?

nonplus — To puzzle; to confound; to perplex; to cause to stop by embarrassment. He has been nonplused by Mr. Dry's desiring him to tell what it was that he endeavored to prove. Spectator. (Webster's 1913.)