| debutto | debut |
| Debye | Debye |
| DEC | Dec |
| DEC Alpha | DEC Alpha |
| decabrista | Decembrist |
| decade | decade |
| decadente | decadent |
| decadenza | decline |
| decadere | decline |
| Decadere del proprio rango | Come down in the world |
| decadico | decadic |
| decadimento | case |
| Decadimento beta | Beta decay |
| decaedro | decahedron |
| decaffeinato | decaffeinated |
| decagonale | decagonal |
| decagono | decagon |
| decagrammo | decagram |
| decalcabile | decal |
| decalcomania | decal |
| decalina | decalin |
| decalitro | decalitre |
| decalogo | Decalogue |
| Decameron | The Decameron |
| Decamerone | Decameron |
| decametro | decametre |
| decano | doyen |
| Decano del collegio cardinalizio | Dean of the College of Cardinals |
| decantare | decant |
| decantatore | decanter |
| decapitare | decapitate |
| decapitato | decapitated |
| decapitazione | beheading |
| Decapoda | Decapoda |
| Decapoli | Decapolis |
| Decarbossilazione ossidativa del piruvato | Pyruvate decarboxylation |
| decathlon | decathlon |
