idiothermic
Self-heating; warmed by processes going on within itself.

idiotical
Synonym of idiotic (“very stupid”).
Simple, unlearned.

idiotick
Obsolete form of idiotic.

idleful
idle

idolatrical
Obsolete form of idolatrous.

idolish
Idolatrous.
Resembling or characteristic of an idol.

idololatrical
idolatrous

idolous
idolatrous

igasuric
Pertaining to, or obtained from, nux vomica or Saint Ignatius's bean; as, igasuric acid

ignant
dumb; stupid

igneoaqueous
Formed by heat and water; denoting an obsolete theory of the formation of granite

ignifluous
Flowing with fire.

ignigenous
igneous

ignivomous
Throwing out fire, as a volcano does.

ignorant
Unknowledgeable or uneducated; characterized by ignorance.
Not knowing (a fact or facts), unaware (of something).
Ill-mannered, crude.
Unknown; undiscovered
Resulting from ignorance; foolish; silly.

ignoranter
comparative form of ignorant: more ignorant

ignorantest
superlative form of ignorant: most ignorant

ignoraunt
Obsolete form of ignorant.

ignoscible
pardonable

ignote
unknown

iliac
Relating to the ilium.

ilial
Archaic form of iliac (“Pertaining to the ilium”).

ilka
Each or every

illaborate
Unlaboured; done or produced lazily or without sufficient effort.

illapsable
Incapable of lapses or error.

illaqueable
Capable of being ensnared or entrapped.

illecebrous
Tending to attract; enticing.

illegall
Archaic spelling of illegal.

illeviable
Not leviable; incapable of being collected or imposed.

illiberal
Restricting or failing to sufficiently promote individual choice and freedom.
Narrow-minded; bigoted.
Ungenerous, stingy.
Not adhering to either liberalism or neoliberalism.

illiberals
plural of illiberal

illicitous
illicit

illimitate
limitless

illimited
Not limited; interminable.

illoyal
Disloyal.

illuminous
bright; clear
luminous; illuminated

illustre
Synonym of illustrious.

illustrous
Without lustre.

imageless
Lacking an image.
Unimaginable.

imaginant
imagining; conceiving, or imaginative

imaginants
plural of imaginant

imaginate
imaginative

imaginous
imaginative

imbannered
Having banners.

imbellic
Not warlike or martial.

imbibitory
absorptive

imbrued
simple past and past participle of imbrue

immaculate
Having no blemish or stain; absolutely clean and tidy.
Containing no mistakes.
Containing no mistakes.
Free from sin; morally pure; sinless.
Of the Virgin Mary or her womb: pure, undefiled.
Lacking blotches, spots, or other markings.

immanifest
Not manifest.

immartial
Not martial; unwarlike.

immatchable
matchless; peerless

immateriate
immaterial

immechanical
Not mechanical.

immediatorial
Not mediatorial; immediate.

immelodious
not melodious

immemorial
That is beyond memory; ancient.

immensible
immeasurable

immerited
unmerited

immeritous
undeserving

immerse
To place within a fluid (generally a liquid, but also a gas).
To involve or engage deeply.
To map into an immersion.

immethodic
Unmethodical.

immethodical
Unmethodical.

immixed
Not mixed; pure.

immixt
Archaic form of immixed.

immoble
Obsolete form of immobile.

immodulated
Not modulated.

immoment
trifling; unimportant

immorigerous
rude; uncivil; disobedient; rebellious

immortified
Not mortified; not having undergone mortification (discipline of the bodily appetites etc.)

immoved
unmoved; motionless; at rest
Unchanged; unaltered; unaffected.

immusical
unharmonious; unmusical

immutate
unchanged

impacable
implacable (unable to be appeased)

imparalleled
unparalleled

imparasitic
Not parasitic.

impardonable
unpardonable

impatible
Impassible.

impatient
Restless, short of temper, and intolerant of delays.
Anxious and eager, especially to begin or have something.
Not to be borne; unendurable.
Prompted by, or exhibiting, impatience.

impavid
fearless, undaunted

impedite
Hindered; obstructed.

impenetrative
Not penetrative.

impenitible
Incapable of repenting.

impennate
Characterized by short wings unsuitable for flying, covered with feathers resembling scales, as in the penguins.

imperate
To command.
To rule, govern.
To direct, motivate.

imperatorial
Commanding; authoritative.
Relating to an emperor, especially of Ancient Rome.

imperatorian
imperial

imperatorious
Imperial; befitting a ruler.

imperatory
imperative

imperdible
Not destructible.

imperfect
Not perfect,
Unisexual: having either male (with stamens) or female (with pistil) flowers, but not with both.
Known or expected to be polyphyletic, as of a form taxon.
Representing a continuing or repeated action.
Lacking some elementary organ that is essential to successful or normal activity.

imperiall
Obsolete form of imperial.

imperious
Domineering, arrogant, or overbearing.
Urgent; intensely compelling.
Imperial or regal.

imperscrutable
Not capable of being sought or understood; inscrutable.

imperseverant
Not persevering; fickle; thoughtless.

imperspicuous
vague; unclear; lacking clarity

impertinent
Insolent, ill-mannered or disrespectful; Disregardful.
Not pertaining or related to (something or someone); Irrelevant or useless.

impertinents
plural of impertinent

impertransible
impermeable

impervial
Synonym of impervious.

impetrable
Capable of being obtained or influenced by petition.

impetrative
Of the nature of impetration; getting, or tending to get, by entreaty.

impetratory
begging; imploratory

impierceable
Not capable of being pierced; impenetrable.

impiteous
Not showing pity or mercy.

implacental
Not having a placenta (said of e.g. marsupials and monotremes).

implacentals
plural of implacental

impleasing
unpleasing; displeasing

impliable
not pliable; inflexible; unyielding

implicate
To show to be connected or involved in an unfavorable or criminal way.
To imply, to have as a necessary consequence or accompaniment.
To imply without entailing; to have as an implicature.
To fold or twist together, intertwine, interlace, entangle, entwine.

implicit
Suggested indirectly, without being directly expressed.
Contained in the essential nature of something but not openly shown.
Having no reservations or doubts; unquestioning or unconditional; usually said of faith or trust.
entangled, twisted together.

implumed
not plumed; without plumes or feathers

impolished
Synonym of unpolished.

impolitical
Obsolete form of impolitic.

imponderous
imponderable

impopular
Unpopular.

importable
Insupportable, unbearable.

importables
plural of importable

important
Having relevant and crucial value; having import.
Pompous; self-important.

importanter
comparative form of important: more important

importantest
superlative form of important: most important

importless
meaningless

importunable
Heavy; insupportable.

importune
To bother, irritate, trouble.
To harass with persistent requests.
To approach to offer one's services as a prostitute, or otherwise make improper proposals.
To import; to signify.

importuous
Without a port or harbour.

imposterous
fraudulent; pretending to be someone else

impostrous
Characterized by imposture; deceitful.

impostured
Done by imposture.

impotent
Lacking physical strength or vigor; weak
Lacking in power, as to act effectively; helpless
Incapable of sexual intercourse, often because of an inability to achieve or sustain an erection, having impotentia coeundi.
Sterile
Lacking self-restraint

impoverisht
Obsolete form of impoverished.

impowered
Obsolete spelling of empowered.

impracticable
Not practicable; impossible or difficult in practice.
impassable (of a passage or road)
unmanageable

impracticables
plural of impracticable

impregnant
Not pregnant; unfertilized or infertile.

impregnants
plural of impregnant

imprejudicate
Without prejudice; impartial.

impremeditate
Unpremeditated.

imprenable
Obsolete form of impregnable.

improbative
Implying, or showing, improbation; disapproving.

improbatory
disapproving

improfitable
Synonym of unprofitable.

improlific
not prolific

imprompt
Not prompt; delayed.
Not ready.

impropitious
Not propitious; unfavourable.