irritability

Etymology

From Latin irritabilitās.

noun

1. The state or quality of being irritable; quick excitability
   irritability of temper
2. (physiology) 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.
   We find a renitency in ourselves to ascribe life and irritability to the cold and motionless fibres of plants. 1800, Erasmus Darwin, Phytologia, Or the Philosophy of Agriculture and Gardening
   1835, Samuel Taylor Coleridge (d. 1834), Specimens of the Table Talk There is growth only in plants; but there is irritability, or, a better word, instinctivity, in insects.
3. (medicine) A condition of morbid excitability of an organ or part of the body; undue susceptibility to the influence of stimuli.