Definition of "Vex" :

verb: be a mystery or bewildering to

"A vexing problem."

verb: subject to prolonged examination, discussion, or deliberation

"Vex the subject of the death penalty."

verb: change the arrangement or position of

verb: disturb the peace of mind of; afflict with mental agitation or distress

verb: cause annoyance in; disturb, especially by minor irritations