榻とう背はいとうはいMeanings1nounback of a chairRare, technical term for the backrest of a chair. In everyday Japanese, 背もたれ is the standard word.この古ふるい椅い子すは榻とう背はいが高たかく、姿し勢せいを正ただして座すわれる。This old chair has a high backrest, allowing one to sit with proper posture.