の至り|のいたり

1. 1The height or extreme of a feeling such as honor or embarrassment, or of an evaluation such as unworthiness or folly, used in formal speech.Ex. 1
2. 2In the idiom 若気の至り, a rash act attributed to one's youth.Ex. 2

A highly formal expression, typical of speeches, acceptance remarks, formal letters and apologies. It most often conveys the speaker's own feelings or a humble self-assessment (不徳の至り). It can also pass judgment on something, as in 愚の至り ('the height of folly'). The idiom 若気の至り looks back on past mistakes, often in an apologetic or self-excusing tone. It resembles の極み but is more fixed and ceremonial.

• 1.
  の極みN1「の極み」 attaches to a wider range of nouns, works with both positive and negative evaluations, and can objectively describe a state, as in 「贅沢の極み」; 「の極みに達する」 is also possible. It has less ceremonial flavor and lacks idiomatic meanings like 「若気の至り」.
• 2.
  極まる・極まりないN1「極まる・極まりない」 attaches directly to na-adjective stems without 「の」, and is mostly used for harsh evaluations of behavior or situations, as in 「無礼極まりない」; its tone is stiff and lacks the humble politeness of a formal address, so it is generally not interchangeable with 「の至り」.
• 3.
  限りだN1「限りだ」 attaches not only to emotion nouns like 「感激」 but also to emotion adjectives like 「寂しい」 and 「残念な」; it only expresses strong feelings, carries no evaluative or idiomatic sense like 「若気の至り」, and is less formal than 「の至り」.
• 4.
  といったらないN1「といったらない」 is neutral in register and attaches to both nouns and adjectives, expressing strong feelings about the nature or state of something, with either praise or criticism; 「の至り」 mostly attaches to fixed Sino-Japanese nouns and is used on formal occasions to express gratitude, humility, and the like, so the two are generally not interchangeable.
• 5.
  に至ってはN1「に至っては」 attaches to nouns and, after a list of examples, picks out the most extreme case of the same kind, meaning "as for..., it is even more so," often with criticism; 「の至り」 expresses emotions or evaluations reaching their peak and is also used in 「若気の至り」. Similar in form but different in meaning, they cannot be interchanged.
• 6.
  んばかりにN1「んばかりに」 attaches to the negative stem of a verb and metaphorically describes an action that is about to happen, often depicting someone else's expression or demeanor; 「の至り」 attaches to Sino-Japanese nouns to express the peak of emotion or evaluation, or appears in 「若気の至り」, with a formal tone. They cannot be interchanged.

の極み and 極まる・極まりない also express an extreme but combine with a wider range of words (贅沢の極み, 失礼極まりない), while 限りだ follows adjectives of feeling (嬉しい限りだ) and といったらない is a more emotional, conversational way to say something is beyond words. に至っては ('as for, going so far as') and んばかりに ('as if about to') do not express 'the utmost degree' at all.