Translation guide
The English word "deficiency" refers to a lack or shortage of something needed, or a weakness or flaw. In Japanese, the best translation depends on whether you mean a shortage of a resource, a nutritional or medical lack, a personal weakness, or a formal defect.
Use when referring to an insufficient amount of a resource, supply, or necessary element.
The most common and versatile word for a shortage or insufficiency. Used for tangible things like money, staff, or materials, as well as abstract things like sleep or exercise.
資金不足でプロジェクトが遅れている。
The project is delayed due to a deficiency of funds.
睡眠不足は健康に悪い。
Sleep deficiency is bad for your health.
A more formal or technical term for a severe lack or scarcity, often used in medical, nutritional, or economic contexts.
ビタミンDの欠乏は骨を弱くする。
Vitamin D deficiency weakens bones.
水の欠乏が深刻な問題になっている。
Water deficiency has become a serious problem.
Refers specifically to the amount that is lacking; the shortfall or deficit.
不足分は来月の予算から補填します。
The deficiency will be covered from next month's budget.
Use when talking about a lack of a specific vitamin, mineral, or substance in the body, or a medical condition caused by such a lack.
The standard medical term for a deficiency disease or condition, such as iron deficiency anemia.
鉄欠乏症と診断された。
I was diagnosed with iron deficiency.
カルシウム欠乏症は骨粗しょう症の原因になる。
Calcium deficiency can cause osteoporosis.
A casual, everyday way to say you are not getting enough of something. Often used in conversation.
野菜が足りてないかも。
I might have a vegetable deficiency.
最近、鉄分が足りない気がする。
Lately I feel like I have an iron deficiency.
Use when referring to a shortcoming in someone's character, ability, or performance.
A general word for a fault, defect, or weak point. Can be used for people, plans, or objects.
彼の唯一の欠点は短気なことだ。
His only deficiency is his short temper.
この計画にはいくつか欠点がある。
This plan has several deficiencies.
Literally 'weak point', often used for a vulnerability or area where someone or something is not strong.
Often used in contrast to 長所 (strengths) when evaluating a person's character or a product's features.
Use in legal, technical, or quality-control contexts to indicate a failure to meet a standard or requirement.
Refers to an inadequacy, defect, or something being incomplete, often used for documents, systems, or preparations.
申請書に不備があったため、受理されなかった。
The application was not accepted due to deficiencies.
セキュリティに不備が見つかった。
Deficiencies were found in the security.
A defect or flaw, often used for manufactured products, systems, or genetic defects. Implies something is faulty.
不足 is the everyday word for 'not enough'. 欠乏 is stronger and more formal, implying a serious or critical lack, often used in medical or economic contexts. For general use, 不足 is safer.
人手不足 (common) vs 人手欠乏 (rare/overly dramatic)
staff shortage
English often uses 'deficiency' as a standalone noun, but Japanese usually requires a compound or a phrase specifying what is lacking. For example, 'iron deficiency' is 鉄欠乏症 or 鉄分不足, not just 欠乏.
報告書はシステムのいくつかの不備を指摘した。
The report highlighted several deficiencies in the system.
ビタミンC欠乏症は壊血病を引き起こすことがある。
Vitamin C deficiency can cause scurvy.
彼はコミュニケーション能力に欠点がある。
He has a deficiency in communication skills.
数学が彼の弱点だ。
Math is his deficiency.
彼女は弱点を克服しようと努力している。
She is trying to overcome her deficiencies.
In the interview, I was asked about my strengths and deficiencies.
その車には設計上の欠陥がある。
That car has a design deficiency.
ソフトウェアの欠陥が原因でデータが消失した。
Data was lost due to a software deficiency.