irritability -
A natural susceptibility, characteristic of all living organisms, tissues, and cells, to the influence of certain stimuli, response being manifested in a variety of ways.
irritability -
A condition of morbid excitability of an organ or part of the body; undue susceptibility to the influence of stimuli.
Wikipedia
Irritability is an excessive response to stimuli. The term is used for both the physiological reaction to stimuli and for the pathological, abnormal or excessive sensitivity to stimuli; It is usually used to refer to anger or frustration. Irritability may be demonstrated in behavioral responses to both physiological and behavioral stimuli including environmental, situational, sociological, and emotional stimuli.