Hangul syllable Kags

Type ㅋ, ㅏ, then ㄱ and ㅅ.

On a Korean input method, the two ending consonants combine as final cluster ㄳ, and the full sequence forms one syllable block.

What does 칷 mean by itself?

By itself, 칷 is a syllable, not a complete word.

Inside Korean spelling it contributes one syllable; the surrounding spelling supplies the word and its meaning. A message containing only 칷 leaves the sender's reason unclear.

Why is 칷 written as one block?

Hangul groups consonants and vowels into square syllable blocks.

The first recorded announcement of Hangul dates to 1443; a guide called Hunminjeongeum was published in 1446 to explain the writing system. These dates concern the alphabet's history, not the origin of this particular syllable. Other names for the script included eonmun, gukmun, and gukseo; the name Hangeul spread in the early 20th century.