From Proto-Tai *ɗrwajᴬ (“stairs; ladder”). Cognate with Northern Thai ᨡᩢ᩠᩶ᨶᨯᩱ, ᨡᩧ᩠᩶ᨶᨯᩱ or ᨤᩢ᩠ᨶᨯᩱ, Lao ກະໄດ (ka dai) or ຂັ້ນໄດ (khan dai), Lü ᦃᦹᧃᧉᦺᦡ (ẋuen²ḋay), Tai Dam ꪅꪽꪼꪒ or ꪅꪽꪼꪨ, Tai Dón ꪼꪒ, Shan ၶူဝ်လႆ (khǒ lǎi) or ၶၼ်ႈလႆ (khān lǎi), Phake ကႃလႝ (kālay), Ahom 𑜁𑜠𑜓𑜩 (khaday), Nong Zhuang lae or mboaklae. Doublet of กระได (grà-dai).
The prefix บัน- (and obsolete บรร-) came from the belief that it was derived from Khmer. But Khmer did not have such word. (Cambodia uses ជណ្ដើរ (cŭəndaə).)
| Orthographic | บันได ɓ ạ n ai ɗ | |
| Phonemic | บัน-ได ɓ ạ n – ai ɗ | |
| Romanization | Paiboon | ban-dai |
| Royal Institute | ban-dai | |
| (standard) IPA(key) | /ban˧.daj˧/(R) | |
บันได • (ban-dai)