| Term | Definition |
| heresy | anti-religious opinion |
| heretic | person who maintains opinion contrary to church doctrine |
| heterogeneous | different in kind |
| heyday | a period of success |
| hiatus | a break in the continuity of work series |
| hibernal | pertaining to winter |
| hirsute | hairy |
| histrionic | theatrical |
| holocaust | destruction by fire |
| homily | sermon |
| homogeneous | of the same kind |
| hurtle | to speed |
| husbandry | the study of raising crops and animals |
| hybrid | mongrel; mixed breed |
| hydrophobia | rabies; fear of water |
| hyperbole | exaggeration |
| hypochondriac | one who worries about his health |
| iconoclast | destroyer of idols or images |
| idyll | short poem describing simple living |
| ignoble | dishonorable |
| ignominious | shameful |
| illicit | unlawful |
| imbibe | absorb |
| imbroglio | confused state of affairs |
| immutable | unchangeable |
| impalpable | vague; not understandable |
| impasse | dead end; difficult situation |
| impeach | to accuse |
| impecunious | poor |
| impertinent | irrelevant; rude |
| implicit | absolute; suggested |
| importune | to trouble with requests |
| impugn | to attack by words or arguments |
| impute | to attribute something bad to one another |
| incendiary | inflammatory |
| incipient | beginning to appear |
| incongruous | not harmonious; inappropriate |
| incredulous | skeptical |
| increment | increase |
| incubus | nightmare |
| indigent | poor |
| indolent | lazy |
| indulgence | act of pampering |
| ineffable | beyond words; unspeakable |
| ineluctable | inevitable |
| ineptitude | awkwardness |
| inert | without power to move or react |
| inexorable | unyielding |
| infernal | hellish; outrageous |
| infidel | an unbeliever |