jungseong means (in Korean or the hangul script) a vowel or diphthong in the syllable nucleus. Lexicurio rates it Sui generis — a strength score of 95 out of 100.
noun
- (in Korean or the hangul script) a vowel or diphthong in the syllable nucleus“[…] and one vowel called the medial (jungseong; syllable nucleus).”