Hangul Jongseong Nieun

It marks the syllable’s final consonant. In a decomposed Hangul sequence, this final nieun jamo follows the opening consonant and vowel: 한 spells 한, with ᆫ closing it. A jamo is one Hangul letter component; alone, this one is not a word.

Hangul was created to make writing Korean easier than using Chinese characters. The first recorded mention of Hunminjeongeum, the work introducing Hangul, dates to 1443; its explanatory book appeared in 1446. It describes consonants at the beginning and end of a syllable, with a vowel in the middle. Early Hangul used ㄴ for nieun in either position; Unicode represents the initial ᄂ and final ᆫ separately.

Why does ᆫ look wrong alone?

It lacks the syllable parts it is meant to join. A trailing jamo is designed to follow an opening consonant and vowel. When ᆫ stands alone, Unicode filler behavior supplies the missing slots, so its size or alignment can vary with a font’s support for conjoining Hangul.

A Korean IME chooses initial or final consonants from typing context and normally composes a complete syllable. That makes this isolated trailing form difficult to produce with ordinary keystrokes.