Noah Webster
Disconcert
DISCONCERT, verb transitive [dis and concert.]
1. To break or interrupt any order, plan or harmonious scheme; to defeat; to frustrate. The emperor disconcerted the plans of his enemy. Their schemes were disconcerted.
2. To unsettle the mind; to discompose; to disturb; to confuse. An unexpected question may disconcert the ablest advocate in his argument.