tes·ty 
(tĕstē)
(tĕstē)adj. tes·ti·er, tes·ti·est
Irritated, impatient, or exasperated; peevish: a testy cab driver; a testy refusal to help.
[Alteration of Middle English testif, headstrong, alteration (influenced by Middle English -if, variant of -ive, -ive, as in natif, native) of Old French testu, from Old French teste, head, from Late Latin testa, skull; see TESTON.]
testi·ly adv.
testi·ness n.