Psychiatric term for a state of being easily irritated or provoked. Used in clinical or academic contexts.
Irritability is known as one of the symptoms of depression.
Compound of 易 (i, 'easy') + 刺激 (shigeki, 'stimulus') + 性 (sei, '-ity'), literally 'easily-stimulated nature'. The exact historical derivation is uncertain, but the term follows standard Sino-Japanese word formation patterns.