irascible

If you try to take apart "irascible" in the same manner as "irrational," "irresistible," or "irresponsible," you might find yourself wondering what "ascible" means-but that's not how "irascible" came to be. The key to the meaning of "irascible" isn't the negative prefix ir- (which is used before words that begin with "r"), but the Latin noun ira, meaning "anger." From "ira," which is also the root of "irate" and "ire," came the Latin verb irasci ("to become angry"), which led to French irascible. English speakers borrowed the word from French in the 16th century.