2. Showing anger or resulting from anger.
ETYMOLOGY: From Latin irascibilis (quick to anger), from irasci (to grow angry), from ira (anger). Ultimately from the Indo-European root eis- (passion), which is also the source of irate, ire, hierarchy, hieroglyphic, and estrogen.
USAGE: "Mr. Weir concludes from his large experience that the erection of the feathers is caused much more by anger than by fear. He gives as an instance a hybrid goldfinch of a most irascible disposition, which when approached too closely by a servant, instantly assumes the appearance of a ball of ruffled feathers."Charles Darwin; The Expression of Emotions in Man and Animals; 1872.