| 1 | English | duplicity | Intentional deceptiveness; double-dealing |
| 2 | English | duplex | Double, made up of two parts; Bidirectional;... |
| 3 | Latin | duplex | twofold, double; bipartite, cloven; ambiguous |
| 4 | Latin | plico | I fold, bend or flex; I roll up; I arrive |
| 5 | Proto-Italic | plekāō | — |
| 6 | Proto-Indo-European | pleḱ- | to fold, plait, weave |
| 7 | Proto-Indo-European | pel- | to cover, to wrap; skin, hide, cloth; to fold |