一層|いっそうissou[0]heiban (flat)

1. adverbeven more; still more; all the more; more than ever
   今いままで以上いじょうにいっそう勉強べんきょうに励はげみなさい。↗

   You should study even more than before.
2. nounone layer
3. nounlowest floor (of a building)
4. adverbrather; sooner; preferably

• SynonymなおNeutralWhen it means 'still more', as in 「なお良い」, it is close to 「一層」. It also means 'still', and as the conjunction 「なお、…」 it adds a supplementary remark.
• SynonymもっとNeutralThe most common everyday word for 'more', natural in blunt urging like 「もっと食べて」; the written-leaning 「一層」 does not urge that casually, though 「一層のご支援を」 works.
• SynonymさらにNeutralFor increasing degree the two are interchangeable, but 「更に」 also works as a conjunction ('moreover') or for adding something on top — uses 「一層」 cannot fill.
• SynonymなおなおWrittenArchaic written word for 'all the more'; rarely used on its own today. In everyday use, 「なお一層」 or 「一層」 will do.
• SynonymぐっとCasualColloquial; stresses that a change is suddenly very noticeable, as in 「ぐっと良くなる」. It also covers doing something with force or in one go — senses 「一層」 lacks.
• Synonymいやが上にもいやがうえにもWrittenA written idiom for an already high degree rising even higher, as in 「いやが上にも盛り上がる」. Its range is narrower than 「一層」's.
• RelatedよりNeutralAs an adverb meaning 'more', as in 「より良い社会」, it is more at home in writing and close to 「一層」. Its basic use is as a particle marking comparison or a starting point.

For 'even more', written style takes 「一層」, speech 「もっと」. 「更に」 also covers 'moreover' and adding something on; 「ぐっと」 is for a sudden marked change; 「より」 is written 'more'; 「尚」 also means 'still' or adds a point; 「いやが上にも」 is a written idiom; 「尚々」 is dated.

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

1. 一ひとつの層そう。
2. ひときわ。さらに。ますます。
3. むしろ。思い切おもいきって。