Irritable \Ir"ri*ta*ble\, a. [L. irritabilis: cf. F. irritable. See Irritate.]

1. Capable of being irriated.

2. Very susceptible of anger or passion; easily inflamed or exasperated; as, an irritable temper.

Vicious, old, and irritable. --Tennyson.

3. (Physiol.) Endowed with irritability; susceptible of irritation; capable of being excited to action by the application of certain stimuli.

4. (Med.) Susceptible of irritation; unduly sensitive to irritants or stimuli. See Irritation, n., 3.

Syn: Excitable; irascible; touchy; fretful; peevish.

Source: Webster's Revised Unabridged Dictionary (1913)