Definition of "Irritate" :

verb: excite to an abnormal condition, or chafe or inflame

"Aspirin irritates my stomach."

verb: excite to some characteristic action or condition, such as motion, contraction, or nervous impulse, by the application of a stimulus

"Irritate the glands of a leaf."

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

"It irritates me that she never closes the door after she leaves."