WordNet sense 1 (the psychological state of being irritated or annoyed):

annoyance, vexation, botheration

WordNet sense 2 (the neural or electrical arousal of an organ or muscle or gland):

excitation, innervation

WordNet sense 3 (a sudden outburst of anger):

pique, temper, pique

WordNet sense 4 (an uncomfortable feeling of mental painfulness or distress):

discomfort, soreness

WordNet sense 5 (unfriendly behavior that causes anger or resentment):

aggravation, provocation

WordNet sense 6 (the act of troubling or annoying someone):

annoying