ir

irascible (adj.) easily angered (At the smallest provocation, my irascible cat will begin scratching and clawing.)

iridescent (adj.) showing rainbow colors (The bride’s large diamond ring was iridescent in the afternoon sun.)

irreverence (n.) disrespect (The irreverence displayed by the band that marched through the chapel disturbed many churchgoers.)

irrevocable (adj.) incapable of being taken back (The Bill of Rights is an irrevocable part of American law.)