dấu nặng

dấu (“diacritic”) +‎ nặng (from the fact that the word nặng has the tone written with a dot below)

• (Hà Nội) IPA^(key): [zəw˧˦ naŋ˧˨ʔ]
• (Huế) IPA^(key): [jəw˨˩˦ naŋ˨˩ʔ]
• (Saigon) IPA^(key): [jəw˦˥ naŋ˨˩˨]

dấu nặng

1. (typography) dot below, diacritic used to write the nặng tone in Vietnamese orthography
2. (linguistics) nặng tone, low glottalized tone