Irascible, choleric, splenetic, testy, touchy, cranky, cross mean easily angered or enraged.
Irascible implies the possession of a fiery or inflammable temper or a tendency to flare up at the slightest provocation.
Choleric implies excitability of temper, unreasonableness in anger, and usually an impatient and uniformly irritable frame of mind.
Splenetic implies a similar temperament, but one especially given to moroseness and fits of bad temper which exhibit themselves in angry, sullen, or intensely peevish moods, words, or acts.
Testy implies irascibility occasioned by small annoyances.
Touchy suggests readiness to take offense; it often connotes undue irritability or oversensitiveness.
Cranky and cross often mean little more than irritable and difficult to please.
But cranky may carry an implication of the possession of set notions, fixed ideas, or unvarying standards which predispose one to anger or a show of temper when others (as in their speech, conduct, requests, or work) do not conform to these standards.
Cross, on the other hand, may imply a being out of sorts that results in irascibility or irritability but only for the duration of one's mood.