Definition of: irritability

(ir′ə·tə·bil′ə·tē) noun plural ·ties
1. The state of being irritable.
2. Susceptibility to anger or impatience.
3. Biol. a The responsiveness of living matter or protoplasm in general to changes in external conditions, manifested by motion, change of form, and in other ways; specifically, the response to stimuli characterizing certain tissues or organs of plants and animals. Compare STIMULUS. b A morbid condition of an organ, manifested by undue excitability under the action of a stimulant. Also ir′ri·ta·ble·ness.