noun
six-year molar
Dental term for the first permanent molar, which typically erupts around age six.
六歳臼歯は永久歯の中で最も早く生えてくる。
The six-year molar is the earliest permanent tooth to erupt.
Compound of 六歳 (six years old) and 臼歯 (molar), referring to the age at which this tooth typically appears.