Entry
カクッと
kakutto
Describes a sudden loss of strength, tension, or support causing a sharp bend, slump, or buckling motion.
Meaning
Quick Meaning
It is commonly used to describe knees abruptly buckling due to shock or relief, or the head suddenly dropping forward when a person falls asleep while sitting up.
- knees giving way
- head dropping while dozing
- collapsing suddenly
Sense Map
Joints Buckling
Describes a sudden loss of tension in a joint, such as the knees giving out unexpectedly.
膝がカクッとなる。
Nodding Off
Describes the sharp, sudden dropping motion of the head when falling asleep while upright.
首がカクッと落ちる。
Sudden Collapse
Describes the entire body losing strength and dropping or slumping down instantly.
カクッと倒れ込む。
Usage Note
How to Use
カクッとなる
The most frequent pattern, used when a body part like the knees or neck suddenly gives way.
カクッと倒れる
Used when describing someone collapsing or falling over abruptly due to losing all strength.
カクッと抜ける
Usually paired with the word for strength, indicating power suddenly draining away completely.
How to Use
Common Phrases
膝がカクッとなる
knees buckle
首がカクッとなる
head drops (when dozing)
カクッと倒れる
collapse suddenly
力がカクッと抜ける
strength abruptly drains
Nuance
Context Nuance
| Common Contexts | Nuance | Usage Note |
|---|---|---|
| Dozing off on a train or in class | neutral | This is the standard expression for the embarrassing moment your head snaps down when you lose the fight against sleep. |
| Experiencing immense shock | negative | Frequently used to describe the exact moment a character's knees buckle from receiving terrible news. |
Similar Words
Comparison Table
| Similar Words | When to Use | Not the Same as | Mini Example |
|---|---|---|---|
へたへた へたへた / similar | When collapsing down to the ground from complete exhaustion or inability to stand. | カクッと implies a sharp buckle or joint giving way instantly, while へたへた describes sinking powerlessly to the floor. | へたへたと座り込む。 |
がっくり がっくり / similar | When dropping one's shoulders or head heavily out of immense disappointment. | がっくり strongly carries a psychological weight of despair, while カクッと describes a purely physical snap, slump, or sleepiness. | がっくりと肩を落とす。 |
Usage Note
Common Mistakes
Using it to describe feeling deeply tired after a long day of work.
It only refers to the momentary buckling motion, not the persistent state of exhaustion. Use くたくた for being worn out.
Using it to describe dropping a heavy object.
It is generally used for joints buckling or things snapping. To describe heavy objects tumbling, use ごろんと.
Examples
Examples
立ち上がろうとしたら、急に膝がカクッとなった。
たちあがろうと したら、 きゅうに ひざが カクッと なった。
When I tried to stand up, my knees suddenly gave out.
LiteralDescribes a joint (the knees) suddenly losing its supporting strength.
電車で座っていると、隣の人の首がカクッと落ちた。
でんしゃで すわっていると、 となりの ひとの くびが カクッと おちた。
While sitting on the train, the head of the person next to me suddenly dropped forward.
VisualA very common usage for the physical motion of dozing off.
ゴール直後、ランナーはカクッと倒れ込んだ。
ゴール ちょくご、 ランナーは カクッと たおれこんだ。
Right after crossing the finish line, the runner suddenly collapsed.
LiteralFocuses on the entire body abruptly losing its physical tension and support.
ホッとした瞬間、全身の力がカクッと抜けた。
ホッと した しゅんかん、 ぜんしんの ちからが カクッと ぬけた。
The moment I felt relieved, all the strength suddenly drained from my body.
FigurativeUsed figuratively for tension that instantly turns into physical weakness.
会議中に眠気で頭がかくっと下がった。
かいぎちゅうに ねむけで あたまが かくっと さがった。
During the meeting, my head suddenly dropped due to sleepiness.
VisualAn all-hiragana spelling variation (かくっと) that is also commonly used.
Similar Words
へたへた
hetaheta
Hetaheta describes the state of losing physical strength, especially in the legs, and sinking or collapsing to the ground. Shows collapsing purely from total lack of energy, without a sharp buckling motion.
ごろんと
goronto
Describes a heavy object tumbling over once or a person effortlessly flopping down to rest.
がっくり
gakkuri
Describes a sudden and profound drop in spirit or physical posture caused by sharp disappointment or exhaustion. Focuses on the slumping of posture due to disappointment or sadness.
Questions
Can I use カクッと to describe mental fatigue?
No, it specifically focuses on a sudden physical loss of tension, like the knees giving out or the head drooping.
What is the difference between カクッと and がっくり?
がっくり typically describes slumping due to emotional disappointment, whereas カクッと focuses strictly on sudden physical weakness or dozing.
Is this expression used in formal writing?
No, it is an onomatopoeia used mostly in casual conversation, literature, and storytelling to depict movements vividly.
Source Details
- Entry ID
- 2869493
- Source
- JMdict_english
- Revision
- -
- Review notes
- No special notes
- Active language
- English
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