Translation guide
The concept of 'insufficiency' covers a range of situations where something is not enough, lacking, or inadequate. In Japanese, the most natural expression depends on what is insufficient and the context. Common patterns include using 足りない (tarinai) for tangible shortages, 不足 (fusoku) for formal or abstract deficiencies, and various grammar patterns for 'not enough to do something.'
Expressing that a physical quantity, money, time, people, etc., is not enough.
The most common and versatile way to say 'not enough' or 'insufficient' for countable or measurable things. It is the negative form of 足りる (tariru, 'to be enough').
I don't have enough money.
I didn't have enough time, so I couldn't finish my homework.
A noun/suru-verb meaning 'shortage' or 'deficiency.' Often used in formal or written contexts, or in compound words like 水不足 (water shortage).
Funds are insufficient.
This region suffers from water shortages.
Literally 'not sufficient.' A slightly more formal alternative to 足りない, emphasizing the lack of adequacy.
That explanation is insufficient.
Expressing that something is not enough to achieve a certain goal or action.
Pattern meaning 'not enough to (do something).' Attach to a verb in dictionary form or a noun.
This material alone is insufficient to make a judgment.
His explanation was not enough to convince me.
Pattern meaning 'not enough to the extent of...' Used with adjectives or verbs to indicate insufficiency for a standard.
He is not honest enough to be trusted.
Describing that something like ability, evidence, or quality is lacking or inadequate.
Na-adjective meaning 'insufficient' or 'inadequate.' Commonly used for abstract qualities, preparations, or evidence.
The evidence is insufficient.
Noun/suru-verb meaning 'lack' or 'absence' of something essential. Stronger than 不足, implying a complete lack rather than just a shortage.
I-adjective meaning 'meager,' 'scarce,' or 'poor.' Often used for resources, experience, or creativity. More literary.
Referring to a lack of necessary substances in the body, such as vitamins or sleep.
Used in medical contexts for deficiencies. Often combined with the lacking substance.
Iron deficiency can cause anemia.
I've been suffering from a lack of sleep.
More technical term for 'deficiency,' often used in medical or scientific contexts.
足りない (tarinai) is a casual, everyday word for 'not enough' and is used in speech. 不足 (fusoku) is more formal and often appears in written language or compound nouns. For example, 'I don't have enough money' is naturally お金が足りない, while 'budget shortfall' is 予算不足.
The English noun 'insufficiency' often translates to a verb or adjective phrase in Japanese. Using the noun 不足 is possible but can sound stiff. In conversation, prefer 足りない or 十分じゃない.
His preparation was inadequate.
The lack of communication is the problem.
彼は経験が乏しい。
He lacks experience.
ビタミンC欠乏症
vitamin C deficiency