著しい|いちじるしいichijirushii[5]nakadaka (mid-high)

1. i-adjectivestriking; remarkable; considerable
   科学かがくは著いちじるしく進歩しんぽした。↗

   Science has made remarkable progress.

• Synonym顕著けんちょWrittenAdjectival noun for objective description in formal prose, as in 「顕著な効果」; nearly the same meaning as the headword and often interchangeable, but commoner in writing.
• RelatedかなりNeutralMeans 'quite' or 'considerably', as in 「かなり難しい」「かなりの量」; very common in daily use. Weaker in degree than the headword and does not stress obviousness.
• Related目立つめだつNeutralA verb meaning to stand out or catch the eye, as in 「目立つ服」「欠点が目立つ」; stresses being easily seen, while the headword speaks of great degree.
• Related並み外れなみはずれWrittenWritten word for far beyond the ordinary, of ability, appetite, stamina etc., as in 「並外れた体力」; stresses being above average, while the headword stresses being marked.
• Related希代きたいWrittenWritten word for rarity in the world, as in 「希代の悪人」「希代の名作」; stresses rareness, which the headword does not imply — it speaks of a marked degree.
• Related大したたいしたNeutralA prenominal only, meaning considerable or impressive, often in the negative 「大したことない」; it can only modify nouns, while the headword can serve as a predicate.
• Related異例いれいWrittenWritten word for exceptional or against convention, as in 「異例の早さ」「異例の人事」; stresses departing from precedent, while the headword stresses great degree.
• Related抜群ばつぐんNeutralFor standing out from the crowd, as in 「抜群の成績」; mostly positive. The headword works for both good and bad, as in 「著しい悪化」.
• Related格別かくべつWrittenWritten word for 'special' or 'exceptional', as in 「格別の味」; usually positive, and also works as an adverb. The headword describes the size of a change or gap.
• Related非凡ひぼんWrittenWritten word for extraordinary talent, as in 「非凡な才能」; mostly about human ability, while the headword speaks of changes and degrees.
• RelatedすごいCasualColloquial all-purpose word for amazing or fearsome; the most common in daily speech. The headword leans written and often describes a large change.
• Related異常いじょうNeutralFor abnormal or off the norm, as in 「異常な暑さ」; stresses deviation from the normal and is often negative, while the headword only says the degree is marked.
• RelatedべらぼうCasualColloquial, Edo-flavoured word for an absurdly large degree, as in 「べらぼうに高い」; also covers unreasonable or foolish. The headword is a sober description.
• Related桁外れけたはずれNeutralFor something far beyond normal standards, as in 「桁外れの才能」「桁外れの金額」; stresses exceeding the usual level, while the headword stresses a marked degree.
• RelatedとてつもないNeutralFor something outrageous or off the wall, also of astonishing scale, as in 「途轍もない計画」; carries surprise, while the headword is a calm description.
• Related人並みはずれたひとなみはずれたWrittenOnly used before nouns, for far beyond ordinary people — stamina, ability, talent and the like; the headword is not limited to people and covers changes and gaps too.
• Related途方もないとほうもないCasualFor far beyond common sense or expectation, as in 「途方もない金額」「途方もない夢」; carries surprise, while the headword calmly describes a marked degree.
• Relatedど偉いどえらいCasualColloquial, dialectal and hyperbolic for very large or amazing, as in 「どえらいこと」; in formal settings use the headword or 「大きい」.
• Related桁違いけたちがいNeutralFor scale or degree in a different league, as in 「桁違いの強さ」; stresses comparison with something else, which the headword does not require.
• Related超凡ちょうぼんWrittenWritten and rare today — use 「非凡」 in daily speech; it only praises excellence, while the headword marks degree and fits both good and bad.
• AntonymわずかNeutralAntonym: for very small quantity or degree, as in 「僅かな差」; often placed right before number expressions, opposite to the headword's marked degree.
• AntonymかすかWrittenWritten antonym: faint or barely perceptible, as in 「微かな音」「微かに見える」; opposite to the headword's clearly discernible degree.
• Antonym些細ささいNeutralAntonym: trivial and insignificant, as in 「些細なこと」; speaks of smallness of matters, opposite to the headword's marked degree.

Use 「著しい」 when a degree or change is strikingly large, as in 「成長が著しい」; it leans written. For objective description in formal prose pick 「顕著」; in daily speech say 「すごい」 or 「かなり」; for simply catching the eye use 「目立つ」. 「桁外れ」「並み外れ」 stress being far above the norm, 「途轍もない」「途方もない」 add a tone of surprise, and the antonyms 「僅か」「微か」「些細」 express smallness or faintness.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. はっきり分わかる。程度ていどがはなはだしい。