Hangul syllable Yis

On its own, it is a syllable, not a complete word. Hangul is the Korean writing system; each block combines Korean letters into one written syllable. 읫 is built from initial ㅇ, vowel ㅢ, and final ㅅ. In Unicode’s construction label, “YIS” names that combination; it is not a Korean word meaning.

Hangul was designed as a learnable way to write Korean. The earliest documentary record of its creation dates to 1443; an explanatory text called Hunminjeongeum was reported complete in 1446.

Why does 읫 appear in historical Korean?

It appears inside historical phrases; the surrounding words supply its role. An early Korean-language explanation of Hangul, the Hunminjeongeum eonhaebon, includes 믈읫. A 1590 Korean translation of the Chinese classic Mencius, 맹자언해, contains 天下읫 士 where the classical Chinese text has 天下之士 (“scholars of the world”).

Historical-linguistics research reads Middle Korean ㅅ as a genitive marker—an ending that links nouns, often with an “of” sense. Whether it connects directly to modern Korean 사잇소리, a sound pattern involving ㅅ in some compounds, remains debated.