硬い・固い・堅い・緊い|かたいkatai[0]heiban (flat)
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Which spelling to use
硬い硬い（かたい） is the most common spelling and the recommended choice for beginners; use it for ordinary written Japanese.
固い固い（かたい） is less common than 硬い（かたい）. It is a less familiar alternative spelling, so use it mainly when reproducing a source that uses it.
堅い堅い（かたい） is less common than 硬い（かたい） and has a less familiar feel. Learners should generally choose 硬い（かたい） in their own writing.
緊い緊い（かたい） is the least common of the four spellings and uses an unusual kanji. Learners should normally avoid choosing it in their own writing.
Definitions
- i-adjectivehard; solid; toughesp. 固い and 堅い for wood, 硬い for metal and stone
- i-adjectivestiff; tight; wooden; unpolished (e.g. writing)
- i-adjectivestrong; firm (not viscous or easily moved)
- i-adjectivesafe; steady; honest; steadfast
- i-adjectiveobstinate; stubborn
- i-adjectivebookish; formal; stuffy
Conjugation
| Plain form | 硬い（かたい） |
|---|---|
| Polite (desu) | 硬いです（かたいです） |
| Negative (kunai) | 硬くない（かたくない） |
| polite (ku arimasen) | 硬くありません（かたくありません） |
| Past (katta) | 硬かった（かたかった） |
| Past negative (kunakatta) | 硬くなかった（かたくなかった） |
| Te form (kute) | 硬くて（かたくて） |
| Adverbial (ku) | 硬く（かたく） |
| Conditional (kereba) | 硬ければ（かたければ） |
| kattara | 硬かったら（かたかったら） |
Common forms generated by rule; see the senses for honorific or irregular usage.
Synonyms & antonyms
- SynonymハードCasualColloquial loanword for hard as in tough and demanding: 「ハードな仕事」. Can also mean physically hard: 「ハードなマットレス」.
- Synonym硬質こうしつWrittenWritten word for hard in texture or material, as in 「硬質ガラス」; mostly seen in descriptions of materials.
- SynonymカチカチCasualColloquial mimetic word for frozen or dried hard: 「カチカチに凍る」; also describes a person as rigid or inflexible.
- Related頑丈がんじょうNeutralNeutral word for sturdy and durable, or a strong body: 「頑丈な箱」. Focuses on not breaking easily rather than feeling hard.
- Related丈夫じょうぶNeutralNeutral word for sturdy or healthy: 「丈夫な体」, 「丈夫な布」. Emphasizes lasting without breaking.
- Related強度きょうどWrittenWritten noun for the degree to which something withstands force: 「強度が高い」. A measure, not an adjective.
- Related堅固けんごWrittenWritten word for solid and firm: 「堅固な守り」; also for an unshakable will.
- Related強固きょうこWrittenWritten word for firm and unshakable, mostly abstract: 「強固な意志」.
- Related堅牢けんろうWrittenWritten word for solid, durable buildings or objects: 「堅牢な城」. More formal than 「頑丈」.
- Related剛ごうWrittenWritten word for strength or toughness of character or force: 「剛の者」. Not used for materials.
- Related硬こうWrittenWritten word for hardness as a property, mostly in compounds like 「硬度」, 「強硬」; rarely stands alone.
- RelatedゴリゴリCasualColloquial mimetic word for hard surfaces scraping, or pushing ahead forcefully: 「ゴリゴリ押す」.
- Antonym柔らかいやわらかいNeutralAntonym of 「硬い」: soft, as in 「柔らかいパン」; also flexible thinking.
For hard itself, use 「硬い」. For sturdy, durable things, 「頑丈」 or 「丈夫」; for solid buildings, 「堅牢」 or 「堅固」; for a firm will, 「強固」; frozen hard, 「カチカチ」; tough and demanding, 「ハード」; the opposite, soft, is 「柔らかい」.
Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only
Japanese definitions
Kanji in this word
English equivalents
See also
