not able to occur, exist, or be done

(idiom) inconceivable; unimaginable; unfathomable

(idiom) inevitable; unavoidable

absolutely necessary or essential; impossible to do without

absolutely necessary; essential; cannot be dispensed with

impervious to reason; unreasonable

inextricably linked or too close to be divided

unable to be taken away, surrendered, or detached from its owner or source; typically used in legal or political contexts regarding rights and territory

(idiom) irremediable; unmanageable; out of hand; hopeless

one's contributions cannot go unnoticed; highly meritorious

to be awfully (busy etc)

hard to come by; exceptionally uncommon or precious

to be kept secret; not to be divulged

not a single element can be omitted; every part is essential for the whole

too wonderful for words

unreliable; not to be trusted

once it starts, there is no stopping it

too great or significant to be measured or calculated; inestimable or beyond measure

(idiom) invulnerable; indestructible; impregnable

don't let the opportunity slip by; no time to lose (idiom)

(idiom) to consider oneself unexcelled in the world; to be insufferably arrogant

can be discovered by chance but not sought out or obtained through intentional effort

an event or effect that cannot be reasonably anticipated or controlled, such as an act of God

incomprehensible or impossible to predict; describing someone's mind, character, or motives

force majeure; act of God

not to be mentioned in the same breath or compared equally due to a vast difference in quality, scale, or status

unable to restrain one's anger; in a towering rage

unable to be crossed or passed through, typically referring to physical boundaries or barriers

not necessarily unacceptable; fine; okay

too high to reach; eminent and unapproachable

beyond reform, hope, or salvation; used to describe a person's character or a desperate situation

secure from violation or infringement, especially regarding laws, rights, or sovereignty

(idiom) impatient; eager to do something; unable to wait any longer

unable to wait; extremely impatient

overjoyed; extremely happy (idiom)

One should not judge a person solely by their looks; appearances can be deceiving.

intolerably vulgar

too many to be counted; innumerable

describing a force, momentum, or offensive that is so powerful it cannot be resisted or held back

within sight but beyond reach; unattainable; inaccessible

extremely disgusting, disgraceful, or scandalous in character or reputation

impossible to stop once started

impossible to resist; an irresistible force

to be in a state of extreme anxiety or insecurity such that one feels unable to carry on even for a single day

The idiom advising that family scandals or private troubles should not be publicized to outsiders; don't wash your dirty linen in public.

impossibly stupid

information that must be kept secret or that one is not at liberty to disclose at the moment