easily irritated or annoyed; "an incorrigibly fractious young man"; "not the least nettlesome of his countrymen"
If you describe someone as testy, you mean that they easily become impatient or angry. Ben's getting a little testy in his old age. + testily tes·ti·ly He reacted testily to reports that he'd opposed military involvement. impatient and easily annoyed = irritable (testif , from teste )