WordNet sense 1 ((used of boats) inclined to heel over easily under sail):

crank, tender, tippy

WordNet sense 2 (lacking stability or fixity or firmness):

unstable

WordNet sense 3 (easily irritated or annoyed):

fractious, irritable, nettlesome, peevish, pettish, petulant, scratchy, testy, peckish, techy, tetchy

WordNet sense 4 (having an irritable and unpleasant disposition):

ill-natured