Hangul syllable uss

Alone, 웄 is one Hangul syllable; the surrounding word gives it meaning.

It is assembled from three jamo: initial ㅇ, vowel ㅜ, and final consonant ㅆ, called 쌍시옷. That final consonant is the 받침, or syllable-ending consonant. Unicode’s structural label “uss” comes from those parts; it is not a Korean word translation.

Hangul was created to write Korean speech that Chinese characters did not fit well. The first record of Hunminjeongeum, the name of the new writing system, dates to 1443; an explanatory book of that name followed in 1446. That book describes the letter shapes as modeled on Old Seal Script, an older Chinese writing style, while Hangul’s way of grouping initial, vowel, and final letters into syllable blocks is its own system.

Why does 웄 appear as separate jamo?

It can be stored as one block or as separate jamo.

Unicode can represent a Hangul syllable as one precomposed block or as separate, position-specific jamo. Normalization may expose the separate forms; a Hangul-aware font can shape them into a block, while unsupported shaping can leave the pieces apart.

The familiar breakdown ㅇ + ㅜ + ㅆ shows the initial, vowel, and final. A decomposed Unicode sequence uses position-specific forms of those letters.