低下|ていかteika[0]heiban (flat)

1. noun, suru verb, intransitive verbfall; decline; lowering; deterioration; degradation
   たしかに出生率しゅっしょうりつの低下ていかで子供こどもの数かずが減へり、学校がっこうでも生徒せいとの数かずが少すくなくなっているのは事実じじつですが、しかし、これはまったくもってけっこうなことです。↗

   It's true that there are fewer children due to the falling birthrate, and there are fewer children in the school, but that is all to the good.

• Synonym下落げらくNeutralFor prices and market values falling, as in 「株価下落」; 「低下」 is about ability, quality or level getting worse.
• Synonym低落ていらくWrittenWritten word for value or popularity dropping; in everyday speech use 「下落」 or 「低下」.
• Synonym下降かこうNeutralPosition or figures moving downward, e.g. a plane descending; 「低下」 is about a level getting worse.
• Synonym低減ていげんWrittenWritten word for deliberately cutting costs or risks, as in 「コスト低減」; 「低下」 usually suggests a natural decline.
• Synonym劣化れっかNeutralFor quality or performance degrading, as in 「部品の劣化」; 「低下」 is broader, covering ability and level too.
• SynonymさがるNeutralA verb for going down, as in 「気温が下がる」; 「低下」 is a noun and leans written.
• Synonym減るへるCasualColloquial verb for amounts shrinking, as in 「体重が減る」; 「低下」 is about degree or level.
• Synonym減衰げんすいWrittenWritten word for gradual attenuation, mostly in physics; 「低下」 is more general.
• SynonymさがりNeutralA noun for a drop, mostly in compounds like 「値下がり」; 「低下」 is more formal.
• Synonym減りへりNeutralA noun for decrease or consumption, mostly in compounds; 「低下」 is about degree getting worse.
• Related減少げんしょうNeutralFor numbers or amounts decreasing, as in 「人口減少」; 「低下」 is about degree or quality getting worse.
• Related衰退すいたいNeutralFor strength or vitality fading, as in 「産業の衰退」; 「低下」 is about figures and levels.
• Related減退げんたいNeutralFor appetite, strength or memory fading, as in 「食欲減退」; 「低下」 also covers figures and quality.
• Related悪化あっかNeutralFor a situation getting worse, as in 「病状が悪化する」; 「低下」 is about a level dropping.
• Related衰えおとろえNeutralA noun for weakening or decline with age; 「低下」 leans toward figures and ability.
• Related衰弱すいじゃくNeutralFor the body or nerves weakening, as in 「神経衰弱」; 「低下」 leans toward figures and ability levels.
• Related衰えるおとろえるNeutralA verb for growing weak or declining; 「低下」 is noun-based and leans toward figures.
• Related弱るよわるCasualColloquial verb for growing weak or being at a loss; 「低下」 is the more written word.
• Related減ずるげんずるWrittenWritten word for amounts or degrees decreasing, or making them smaller; in everyday speech say 「減る」 or 「減らす」.
• Related減じるげんじるWrittenAnother form of 「減ずる」, written in tone: to decrease or lessen; in everyday speech say 「減る」.
• Antonym上昇じょうしょうNeutralAntonym on the rise/fall axis: figures or position going up.
• Antonym向上こうじょうNeutralAntonym on the better/worse axis: ability or quality improving.
• Antonym増加ぞうかNeutralAntonym on the increase/decrease axis: quantities growing.

Use 「低下」 when ability, quality or a level gets worse. For falling prices say 「下落」, for shrinking numbers 「減少」, for worsening conditions 「悪化」, for degrading quality or performance 「劣化」, and for physical descent 「下降」. The main antonyms are 「上昇」 and 「向上」.

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

1. 低ひくくなること。
2. 程度ていどが悪わるくなること。