irascible (adj.) Look up irascible at Dictionary.com
late 14c., from Old French irascible (12c.) and directly from Late Latin irascibilis, from Latin irasci "be angry, be in a rage," from ira "anger" (see ire).
Irascible indicates quicker and more intense bursts of anger than irritable, and less powerful, lasting, or manifest bursts than passionate. [Century Dictionary]