103 Adjectives That Start With “I”

“I” is an all-important letter. On its own, it’s the word for self-expression, but it’s also the beginning to some incredible adjectives. An intriguing prospect, right? The nearly infinite array of adjectives that start with “I” gives you an inexhaustible source of inspiring words to play with and include in your increasing vocabulary.

List of Adjectives That Start with I List of Adjectives That Start with I
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Positive Adjectives That Start With “I”

It never hurts to look on the brighter side of life. Having some positive adjectives that start with “I” in your back pocket ensures that you have the perfect words to describe your inimitable friends, industrious coworkers, and incomparable family members.

Adjective

Definition

Synonyms

idiosyncratic

distinctive; particular; individual

unique, quirky, distinct

idyllic

peaceful, tranquil, or pretty

pleasant, pastoral, unspoiled

illustrious

well-known and respected

distinguished, eminent, transcendent

imaginative

having or showing creativeness or resourcefulness

clever, fanciful, inventive

immaculate

spotless; no stains

flawless, perfect, pure

impactful

having a significant or powerful effect

impressive, poignant, stunning

impeccable

the highest standards of propriety; flawless

perfect, spotless, unblemished

important

having great significance or consequence

eminent, influential, outstanding

impressive

leaving a feeling of awe or admiration

moving, inspiring, telling

incomparable

having no common basis for comparison

excellent, superior, unparalleled

incredible

impossible to believe

unbelievable, wonderful, amazing

indefatigable

having tireless persistence

diligent, dogged, unrelenting

industrious

hard-working

ambitious, assiduous, productive

ineffable

too great for words

indescribable, inexpressible, transcendent

infallible

incapable of mistakes or errors

flawless, perfect, unerring

ingenious

clever, talented, possessed of genius

smart, bright, resourceful

inimitable

impossible to copy or imitate

unique, matchless, distinct

innocent

free from sin

blameless, spotless, upright

insightful

showing a deep understanding

astute, discerning, perceptive

inspiring

encouraging someone

motivating, encouraging, influential

intelligent

clever; a high level of intelligence

smart, bright, sharp

interesting

arousing curiosity or interest

fascinating, compelling, intriguing

intrepid

unafraid; fearless

brave, courageous, bold

intriguing

arousing curiosity or interest

interesting, engaging, riveting

intoxicating

causing great happiness

exciting, exhilarating, invigorating

invigorating

filling one with energy or strength

energizing, refreshing, revitalizing

inviting

alluring, making itself wanted or desired

tempting, welcoming, attractive

Negative Adjectives That Start With “I”

At the same time, some moments or people call for more of a negative approach. While you shouldn’t always be an Icy Ivan, some people are just improper and can leave you feeling irate and irritated.

Adjective

Definition

Synonyms

icky

gross; sticky

gooey, vile, displeasing

icy

very cold or, in dealing with people, unfriendly; hostile

aloof, unwelcoming, inhospitable

idealistic

unrealistically aiming for perfection

unrealistic, impractical, lofty

idiotic

incredibly stupid

silly, mindless, witless

illegitimate

not authorized by law

unlawful, illegal, criminal

illicit

forbidden by law or customs; against the law

illegal, outlawed, prohibited

illogical

lacking sense or reason

unreasonable, irrational, nonsensical

immoral

not conforming to the standards of morality

unethical, unscrupulous, disreputable

impassable

impossible to pass or travel through

impenetrable, obstructed, untraversible

impetuous

acting impulsively

impulsive, reckless, foolhardy

impish

inclined to do naughty things for fun

mischievous, devilish, roguish

improper

not in accordance with the rules

inappropriate, unseemly, unbecoming

inapt

unsuitable; unfitting

unfitting, unsuitable, unprofessional

incompetent

lacking the skills to accomplish something

bungling, unskillful, unprofessional

inept

showing no skill

clumsy, unskillful, feckless

inferior

of a lower quality

lesser, substandard, low-quality

infernal

relating to hell; the underworld

hellish, subterranean, chthonic

inglorious

shameful; loss of honor; disgraceful

shameful, dishonorable, disgraceful

insipid

lacking flavor; not exciting or interesting

bland, boring, dull

intransigent

uncompromising; unwilling to see other's views; inflexible

unyielding, uncompromising, stubborn

irascible

easily angered; irritable

quick-tempered, short-tempered, crabby

irate

extremely mad

angry, furious, enraged

irreconcilable

points of view that are so different, they cannot be made compatible

incompatible, incongruous, discordant

irrelevant

beside the point; not important

tangential, extraneous, unimportant 

irritable

having a tendency to be easily angry or annoyed

bad-tempered, touchy, grumpy

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Neutral Adjectives That Start With “I”

Sometimes, you just need a good, middle-of-the-road word to describe your situation. Maybe you’re inside, looking for the perfect indigo shirt, feeling a bit introverted, or want to learn about Indigenous people.

Adjective

Definition

Synonyms

iconoclastic

attacking beliefs or hierarchies; nonconformist

individualistic, nonconformist, critical

illusive

dreamlike; not based in reality

deceptive, imaginary, false

impermeable

does not allow liquid to pass through; insusceptible

airtight, hermetic, sealed

improbable

not likely to happen

impossible, unbelievable, doubtful

immune

protected or exempt; resistant to infection

unaffected, resistant, exempt

inadvertent

not happening through planning

unintentional, unwitting, accidental

inanimate

not alive; lifeless

inert, lifeless, motionless

inclined

leaning away from horizontal or vertical; having a preference

slanted, biased, sloping

inconceivable

not capable of being grasped

unbelievable, extraordinary, mind-boggling

inconspicuous

not easily noticed or visible

concealed, camouflaged, hidden

indicative

suggestive; serving as a sign

suggestive, emblematic, symbolic

indigenous

native to a particular place

endemic, innate, original

indigo

dark blue in color

blue-green, azure, cerulean

intended

planned or meant on purpose

expected, calculated, predetermined

intensive

thorough; concentrated on a specific area

comprehensive, thorough, in-depth

intrinsic

essential; inherent

elemental, underlying, built-in

inside

interior; inner

indoors, internal, central

instant

happening immediately

prompt, on-the-spot, swift

integral

necessary; essential

fundamental, vital, indispensable

intense

possessing extreme force or fierce strength

fierce, great, extreme

intricate

containing a lot of complex parts

complicated, detailed, elaborate

introverted

having a personality that is shy or more preoccupied with oneself

shy, reserved, withdrawn

invincible

unconquerable; indestructible

invulnerable, indestructible, unbeatable

ironic

occurring in a way that is the opposite of what was expected

sardonic, sarcastic, satirical

irrevocable

irreversible; not able to change

permanent, unchangeable, fixed

itty-bitty

tiny

small, diminutive, minuscule

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Fun and Uncommon Adjectives That Start With “I”

The world of adjectives that start with “I” is imbued with an infinite array of fun words. Whether you need to describe something that’s fishlike (ichthyic) or find the right fire-adjacent word (igneous or inflammable), the letter “I” has you covered.​

Adjective

Definition

Synonyms

ichorous

relating to any acrid, watery fluid

melted, aqueous, dissolved

ichthyic

fishlike

piscine, fishy

idiomatic

related to a particular language or dialect; having a distinct style

dialectal, colloquial, vernacular

idiopathic

occurring spontaneously or without known cause, typically of a disease

spontaneous, unexplained, unidentified

igneous

of or relating to fire; (in geology) produced under processes involving intense heat

burning, molten, roasting

illaudable

unworthy of praise

shameful, unworthy, disreputable

imbricate

overlapping in sequence; resembling overlapping tiles

overlapping, covered, enveloped

impecunious

having little money

penniless, poor, destitute

impromptu

without planning or forethought

improvised, unscripted, spur-of-the-moment

imprudent

unwise; without thought of consequences

reckless, rash, careless

impudent

disrespectful or offensively bold

rude, disdainful, brazen

impugnable

open to question or debate

debatable, doubtful, precarious

inauspicious

unfavorable, not of good omen

unfortunate, baleful, ominous

inceptive

related to the beginning of something

nascent, earliest, foremost

incredulous

of a person unable or unwilling to believe

unbelieving, skeptical, unconvinced

incognito

having your identity concealed

disguised, concealed, anonymous

incorrigible

beyond correction; firmly fixed; not easily changed

stubborn, uncorrectable, incurable

incumbent

necessary as an obligation or duty

binding, compelling, urgent

infinitesimal

extremely small

microscopic, minuscule, tiny

inflammable

easily set on fire

flammable, incendiary, combustible

innoxious

harmless

nontoxic, safe, bland

invertebrate

without a backbone; having no strength of character

spineless, ineffective, inefficacious

iridescent

shining with numerous colors like a rainbow

lustrous, shimmering, opalescent

ironclad

protected in iron; impossible to change or contradict

inflexible, unwavering, firm

itinerant

traveling from place to place

wandering, roving, migratory

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Example Sentences for Adjectives That Start With “I”

You saw the words, but seeing them in action can help you understand how inviting or irrelevant they might be.

  1. Stop that infernal racket!
  2. The book we bought our host was an incredible Irish cookbook.
  3. His dining room was painted a deep shade of indigo that made the place seem fit for a king.
  4. When we looked around his house, we realized that his taste was impeccable.
  5. She was an undeniably beautiful girl, but her intelligent air made her even more attractive.
  6. When we arrived very late, our host was so irate he made us find another place to stay.
  7. The waiter's icy manner didn't sit well with the customers.
  8. That icky new candy bar isn't selling well.
  9. The invincible defense of the football team took them all the way to the playoffs.
  10. Her impactful speech made me rethink everything about my life.
  11. The teacher’s insightful analysis helped the class understand the books’ themes.
  12. It felt great to escape the loud, busy city and enjoy the quiet, idyllic countryside, even if it only lasted one week.
  13. The professor’s insipid lecture put most of the class to sleep.
  14. Even though he’s really talkative around his friends, he tends to be more introverted around strangers.
  15. Our truly indefatigable friend spent her weekend babysitting her niece, running a marathon, and hosting a party, all without needing to rest.
  16. I was tired and exhausted in the morning, but an invigorating lunch with my friend was all I needed to keep going.
  17. The toy has a lot of intricate pieces, so please be careful when handling it.
  18. No one seemed willing to talk at dinner, so she gave an impromptu speech about her vacation.
  19. His quiet demeanor and lack of participation was indicative of a bad morning.
  20. Even though his attempt at making dinner was an irrevocable failure, he knew what he did wrong, so he could do better next time.
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Other “I” Words for Your Eyes

Indeed, now you have intensive knowledge of adjectives that start with “I,” but don’t stop there. Learning other words that start with “I” is a great way to improve your overall reading and writing abilities.