Doubled ㅅ (siot)
- A jamo (letter) of the alphabet of the Korean writing system, hangeul.
- In North Korea, ㅆ is called 된시읏 (doensieut), "strong ㅅ (sieut)" and is the eighteenth jamo. In South Korea, it is called 쌍시옷 (ssangsiot), "doubled ㅅ (siot)" and is the eleventh jamo.
- ㅆ is pronounced as a sibilant with tense phonation (IPA: [s͈] or [z̬]), i.e. similar to the English s, but with a stiff tongue and glottal opening.