快 (kuài) means "fast" with 7 strokes, radical 忄 (heart), HSK 2 on the new exam.
Pronunciation
Meaning
Primary: fast
Etymology
Oracle-bone origin
快 is a phono-semantic compound not attested in oracle bone script. It combines 忄, the heart radical, as the semantic component with 夬 (guài) as the phonetic. 夬 itself depicts a hand holding a jade ring or thumb-ring used to draw a bowstring, suggesting a sharp release; this notion of swift release connects to the modern sense.
Form evolution
The character appears in seal script with 忄 on the left and 夬 on the right, and the form has been remarkably stable since. Clerical script squared the strokes, and modern 楷书 kept the same arrangement. Because 快 is a later compound, there is no meaningful pictographic earlier form to trace.
How the meaning evolved
The earliest recorded meaning is pleased or gratified, preserved today in 愉快, 痛快, and 快乐. The sense of fast or quick developed by extension, likely through the idea of a sharp, snappy quality, and by the Tang dynasty 快 commonly meant swift. A third sense, sharp (as of a blade), survives in 快刀 and reflects the original 夬 imagery of a sharp release.
Cultural note
The three senses happy, fast, and sharp all coexist in modern Mandarin: 快乐 (happy), 很快 (fast), 快刀斩乱麻 (a sharp knife cuts tangled hemp, meaning decisive action). Learners usually meet the fast sense first and are surprised to find that the happy reading is historically older, visible in the greeting 新年快乐.
Mnemonic
A heart that breaks free — fast, happy
Decomposition
Breaking a character into its components makes it far easier to recall. Each component above links to its own detail page.
Basic info
| Pinyin | kuài |
| Meanings | fast |
| Stroke count | 7 strokes |
| Radical | 忄 (#61: heart) |
| New HSK exam | Recognise at HSK 2 |
| Frequency | #232 most common |
Example sentences
Words containing 快
Related characters
Similar meaning (abstract)
On the new HSK 2 exam
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Frequently Asked Questions
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Reviewed by RJ Murray, Founder, HSK Lord.