Translation guide
The English word "inadequate" describes something that is not enough or not good enough. In Japanese, the best translation depends on whether you mean insufficient in quantity, lacking in quality or ability, or not meeting a standard.
Use when something is not enough in number, amount, or degree.
The most common and versatile word for "inadequate" in the sense of being insufficient or not enough. Can be used in both formal and casual contexts.
食料が不十分だ。
The food supply is inadequate.
その説明は不十分だった。
The explanation was inadequate.
A more casual, everyday word meaning "not enough" or "lacking." Often used in spoken Japanese.
お金が足りない。
I don't have enough money. (The money is inadequate.)
A noun/suru-verb meaning "shortage" or "insufficiency." Often used in formal or written contexts.
人手不足で仕事が進まない。
Work isn't progressing due to inadequate staffing.
Use when someone or something fails to meet a required standard of quality, skill, or performance.
Also used for quality/ability. It implies that the level is not sufficient to meet expectations.
彼の準備は不十分だった。
His preparation was inadequate.
Means "inappropriate" or "unsuitable," often used when something is not adequate for a specific purpose or context.
Refers to a defect, flaw, or inadequacy in a system, plan, or preparation. Often used in formal or business contexts.
計画に不備があった。
There were inadequacies in the plan.
Use when describing a person's feeling that they are not good enough, competent, or worthy.
Literally "have no confidence in oneself." This is the most natural way to express feeling inadequate about one's abilities.
彼は自分に自信がないように見える。
He seems to feel inadequate.
Means "to have an inferiority complex." A more psychological term for deep-seated feelings of inadequacy.
彼女は姉に対して劣等感を抱いている。
She feels inadequate compared to her older sister.
Describes feeling disappointed in oneself for being inadequate or pathetic, often in a situation where one should have done better.
不十分 (fujuubun) is more formal and objective, often used in written or official contexts. 足りない (tarinai) is casual and subjective, common in everyday speech. Use 不十分 when reporting facts; use 足りない when expressing personal feelings of lack.
Saying 不十分な人 (fujuubun na hito) sounds unnatural. Instead, describe the specific inadequacy or use phrases like 能力不足 (nouryoku busoku - lack of ability) or 自信がない (jishin ga nai - lacking confidence).
安全対策は不十分だった。
The safety measures were inadequate.
日本語を話すとき、自分に自信がなくなる。
I feel inadequate when I speak Japanese.
この設備は現代の基準には不適切だ。
This equipment is inadequate for modern standards.
Expresses a feeling that something is lacking or not quite satisfactory, often subjectively. It's like "leaves something to be desired."
彼の説明は物足りなかった。
His explanation was inadequate (unsatisfying).
自分が不甲斐なくて情けない。
I feel miserable about my own inadequacy.