| Term | Definition |
| indolent | lazy |
| ineffable | cannot be expressed in speech; unutterable |
| inexorable | not to be persuaded, moved, or affected by prayers or entreaties |
| insolvent | bankrupt |
| insuperable | unbeatable |
| intractable | stubborn |
| irreproachable | blameless; faultless |
| jocular | said or done as a joke |
| lampoon | ridicule |
| lassitude | weariness; tiredness |
| laconic | brief and to the point |
| laggard | slow; sluggish |
| lithe | flexible |
| lurid | wild; sensational |
| meander | turn in its course |
| mercenary | interested in money |
| mercurial | changing; capricious |
| mirth | laughter |
| misanthrope | one who hates mankind |
| misnomer | wrong name; incorrect designation |