definition of
irritable

[1] #1 irritable s. [cranky, fractious, nettlesome, peevish, peckish, pettish, petulant, scratchy, testy, tetchy, techy] easily irritated or annoyed; "an incorrigibly fractious young man"; "not the least nettlesome of his countrymen". wn

[2] #2 irritable s. abnormally sensitive to a stimulus. wn

[3] #3 irritable s. [excitable] capable of responding to stimuli. wn